refactor(street-level): the panel cuts deferred until the new sources landed

HAL-530 left five panel cuts until Street View, KartaView and Panoramax
were in:

- SINCE is a select of the nine windows instead of a slider with its own
  thumb-sync code; a link's day count between them gets its own option and
  the tooltip names the cut-off date.
- IMAGERY and FIT/FILL are toggle buttons (aria-pressed), each a tab stop,
  instead of ARIA radiogroups with roving tabindex and arrow-key handling.
- The panel opens by itself only when a photo opens (a map or line click
  would load it out of sight); a switch-on no longer opens it, so the
  enable-origin subscription goes.
- Clean View, recording and the cockpit call shrinkViewer() as they hide
  the panels, instead of a MutationObserver on <body> classes.
- FIT/FILL stays (three providers use it) but is no longer kept in
  localStorage: each session starts at FIT.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

docs/CURRENT-STATE.md

@@ -3484,7 +3484,12 @@ Mapillary token, Street View on Google 3D with a Google key), the layer
 reports it (`keyAlternatives`), and the panel's KEY REQUIRED, its coverage
 line and the layer row's tooltip say to light it. The
 viewer sits under the header with EXPAND, FIT/FILL and close above the
-image. SINCE is a stepped slider whose readout names the cut-off date.
+image; FIT/FILL starts at FIT each session. IMAGERY and FIT/FILL are rows of
+toggle buttons (`aria-pressed`), each its own tab stop. SINCE is a select of
+the nine windows; a link's day count between them gets its own option, and
+the tooltip names the cut-off date. The panel opens by itself only when a
+photo opens (a click on the map or a line would otherwise load it out of
+sight), never when the layer is switched on.
 
 MapillaryJS loads on the first photo. Opening one frames it with a single
 camera flight through the application's deferred navigation (`begin` /
@@ -3493,7 +3498,8 @@ if newer navigation took the camera while the photo loaded; closing the photo
 cancels it. EXPAND is the browser's Fullscreen API on the viewer element; on
 iPhone, which has no element fullscreen, the viewer opens as a top-layer
 popover instead (hidden where neither API exists). Clean View, recording and
-the cockpit take an expanded photo out of full screen. At phone width the
+the cockpit take an expanded photo out of full screen: the shell calls the
+panel's `shrinkViewer()` as it enters them. At phone width the
 viewer height comes from the rail band so the whole photo fits.
 
 Providers implement the contract in `src/layers/streetLevel/registry.js`. The
@@ -3586,7 +3592,7 @@ lookup asks the photo API for the projection (`SPHERE`/`PLANE`; it ignores
 photos are near but none passes, the panel says so), and the cones pass on
 each photo's projection and upload date. The provider declares
 `sinceBasis: 'upload'`, so while it is lit the panel shows "KartaView: by
-upload date" under the SINCE slider (`sinceNote` in the UI state). Tiles come uncompressed and
+upload date" under the SINCE select (`sinceNote` in the UI state). Tiles come uncompressed and
 uncacheable, so the last 24 decoded tiles are kept for 10 minutes while
 KartaView is lit (`createTileCache`, dropped when it is switched off); one
 that does not answer in 20 s is asked once more, and one that is not a line