fix(transit): keep the real silhouettes under sensor presets, make the selected trail visible, put Transit in Movement (#596)

## Changes

Follow-up to #587 after the owner's first look at the merged transit layer on Google 3D tiles.

- **Sensor presets keep the real silhouettes.** Under NVG, thermal (white-hot, black-hot, Ironbow) and noir, vehicles are the same silhouettes as in normal view, filled opaque white with a 2 px dark halo, at the CRT display sizes (26 px fleet, 39 px selected). The solid rounded "signature" bodies are gone.
- **The selected vehicle's trail is visible.** The retained history is now draped onto 3D tiles and terrain (`GroundPolylinePrimitive`, `ClassificationType.BOTH`, the way the traffic heat-lines are drawn), 3 px core over a 5 px dark backing, per-segment age colour, a short draped head clipped to the sprite. Two defects kept it off screen before: Cesium's per-instance attribute getters return copies, so the renderer's show/colour edits were discarded, and a marker did not recover after the camera jumped to it, which hid the trail with it. Trail geometry is now prepared on selection independent of floor resolution and marker visibility; sparse long intervals (rail) keep a bounded marker corridor instead of dropping the interval; classification survives map-source changes.
- **Transit sits in the Movement panel group** between Street Traffic and Bike Share (the panel orders by `PANEL_GROUPS`, not by catalog order; the catalog is moved too).

## How it was verified

- `npm run format:check` (854 files), `npm run check:boundaries`, `npm test` (4,062 passing), `npm run build` clean; tracking regression 109/109 in a real browser on Google 3D tiles.
- Browser harness (`scripts/qa-transit.mjs`), keyed on Google 3D tiles and keyless: keyed 194 pass, with the trail pixel check passing at 300, 600 and 900 m; the remaining keyed failures are the per-frame allocation gate already recorded as a follow-up from #587 (CPU and frame time within budget), four readability lines at threshold edges, and the card-anchor check now counting frames where the selected marker is legitimately off screen; keyless 193 pass with the remaining misses being threshold edges on the thin tram silhouette (centre 0.83–0.88 against 0.85) and one bus ring 0.28 against 0.25 on a pure-white roof.
- New harness checks: `Google 3D selected trail visible at 6 of 8 projected samples` (repeated off/on framebuffer captures at 300/600/900 m, samples outside the sprite footprint, a background-change negative control; fails on main, passes here), a camera-arrival check (select a moving vehicle, `setView` onto it, marker shown and trail body drawn within 2 s), `PANEL_ORDER` pinned, raster tests comparing every sensor raster's mask and aspect ratio to the normal silhouette.
- Direct look on a keyed build: a live CapMetro bus at 30 m/s selected through the layer API draws its draped trail along the highway lane (harness capture `keyed-600m-trail-visible.jpg`).
- Adversarial review by Codex Astra before the last two fix passes (stack-switch classification, marker corridor under the vertex cap, pixel-gate loophole), all three fixed with regressions.

Docs: `docs/CURRENT-STATE.md` and `CHANGELOG.md` updated in this PR. No data-source changes.

README.md

@@ -284,9 +284,9 @@ Fifteen layers and map sources. **Thirteen have a keyless path.** Some offer add
 | 🚗 **Traffic**              | Simulated vehicles on OSM roads. With TomTom, live flow speeds drive the simulation and congestion colors below ~8 km; individual vehicle positions are not live observations                                                                                                                                                                                                       | TomTom + OSM                            | 🟢 simulation · 🟡 live flow speeds                                                                 |
 | 📹 **CCTV Mesh**            | ~3,600 public cameras projected _into_ the 3D space — Austin · Texas (TxDOT) · California (Caltrans) · London (TfL) · Ontario (511) · Finland (Fintraffic) · British Columbia (DriveBC) · Estonia (Tallinn, Tarktee) · New South Wales (Live Traffic NSW) · Calgary. Positions are published; poses are estimated priors **you calibrate by dragging a gizmo on the camera itself** | City APIs                               | 🟢                                                                                                  |
 | 📻 **Radio**                | Geolocated world radio with an **analog tuner** — drag the needle across up to 750 stations and the globe flies to each broadcaster                                                                                                                                                                                                                                                 | Radio Browser / broadcasters            | 🟢                                                                                                  |
+| 🚌 **Transit**              | Live buses, trams, metros, trains and ferries with delayed playback between reports, selected-vehicle trails, and mode-coloured DETECT labels — Boston, Austin, Minneapolis, Helsinki, the Netherlands, Norway, South East Queensland                                                                                                                                               | Operator GTFS-Realtime feeds            | 🟢                                                                                                  |
 | 🚲 **Bikeshare**            | Live station availability                                                                                                                                                                                                                                                                                                                                                           | GBFS                                    | 🟢                                                                                                  |
 | 🧭 **Directions**           | Click A and B on the globe for a street-following drive, walk or cycle route draped on the terrain with turn-by-turn steps — then FLY the camera along it. No key, no geocoder, no mic                                                                                                                                                                                              | OSRM on FOSSGIS servers (OpenStreetMap) | 🟢                                                                                                  |
-| 🚌 **Transit**              | Live buses, trams, metros, trains and ferries with delayed playback between reports, selected-vehicle trails, and mode-coloured DETECT labels — Boston, Austin, Minneapolis, Helsinki, the Netherlands, Norway, South East Queensland                                                                                                                                               | Operator GTFS-Realtime feeds            | 🟢                                                                                                  |
 | 🔥 **Active Fires**         | Live NASA FIRMS detections, trailing 24h                                                                                                                                                                                                                                                                                                                                            | NASA FIRMS                              | 🟡                                                                                                  |
 | 🚀 **Space Missions**       | Rolling 30-day launches with payload, stage, and recovery detail                                                                                                                                                                                                                                                                                                                    | Launch Library 2                        | 🟢 (🟡 optional token raises the allowance)                                                         |
 | 🎖️ **Mapped Installations** | Viewport-bounded military-site context from community mapping — incomplete by nature, and labeled that way                                                                                                                                                                                                                                                                          | OpenStreetMap                           | 🟢                                                                                                  |