feat(annotations): draw on the world by hand (#547)

Supersedes #235 by @cora-fresh-labs, ported onto the current component layout with fixes from review.

Verified before merge: format, package boundaries, unit suite, build, and the browser tracking suite; a browser harness for the change where one applies; adversarial review applied.

Future work (not in this PR): hand-drawn marks do not persist across a reload today, and neither do spoken annotations; there is no storage layer for marks. The natural home is Scenes: a drawing that belongs to a shot and persists per shot, so a scene animation can carry its own marks. Needs an owner.
Co-authored-by: Clint Borle <[email protected]>

README.md

@@ -243,6 +243,8 @@ Twenty-eight tools, four jobs — the commands below come straight from the prod
 **🖊️ Annotate it** — a whiteboard over the real world:
 > 🗣️ *"Outline the state of Texas."* · *"Annotate the Texas State Capitol and its grounds"* — it draws the **actual enclosing boundary**, not a circle. · *"How far is the Eiffel Tower from the Louvre?"* — a connector arrow appears and it speaks the distance. Everything persists until you say *"clear the map."*
 
+**✍️ Or draw it yourself** — DISPLAY ▸ **Draw**: pick Area, Line or Pin, click the vertices on the real world, double-click to finish, label it. Same whiteboard, same persistence, no microphone needed.
+
 ![Zilker Park and Lady Bird Lake drawing onto the 3D city as persistent vector annotations, by voice](docs/media/01-voice-annotate-zilker.gif)
 
 ![A spoken distance measurement spanning an airport, inspected from orbit](docs/media/04-airport-distance.gif)