docs: CONTEXT.md — mark camera pipeline end-to-end verified

Camera rig-86d978 registers + lists in the API/dashboard with status
ingested. Add decisions for modernc/sqlite datetime scanning and legacy
camera-id migration.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CONTEXT.md

@@ -176,6 +176,13 @@ reach; the Pi pulls instead.
     now defaults the service user to `$SUDO_USER`.
 12. **Hub embeds the frontend** via `//go:embed all:src/dist`; Vite builds into
     `cmd/server/src/dist` (a committed `index.html` placeholder keeps the embed valid).
+13. **SQLite/modernc datetime:** `modernc.org/sqlite` returns a `COALESCE()`/expression
+    as a raw string (no type affinity) → can't scan into `time.Time`. Scan plain
+    `DATETIME` columns (returned as `time.Time`) via `sql.NullTime`; `ListCameras`
+    `COALESCE`s NULL int/bool status columns. Nodes send no usable timestamp on
+    status/heartbeat (numeric `millis()`) — the hub ignores it / stamps server-side.
+14. **Legacy id migration:** `handleAnnounce` migrates a MAC registered under a
+    different `camera_id` (e.g. a pre-self-id `cam-NNN`) to the node's self-id.
 
 ## 10. Conventions
 
@@ -192,13 +199,11 @@ reach; the Pi pulls instead.
 - Full CI/CD loop proven: commit → CI build → `dev-latest` → Pi self-update
   (checksum, atomic replace, health-check) → service active.
 - C6 (fw `0.4.0`) joins RemoteRig, connects to the broker, announces as `rig-86d978`,
-  publishes status. ESP-01S UART link alive.
+  and is **registered + listed** in `GET /api/v1/cameras` and the dashboard, with
+  status/heartbeat ingested cleanly. Shows `online:false` / zeros until a GoPro is
+  attached (expected on the bench). ESP-01S UART link alive. **End-to-end verified.**
 
 **In progress / unresolved:**
-- **Verifying the hub registered `rig-86d978`** — needs confirmation that the hub is on
-  build `18db26c2` (Option B) and that the camera is in the DB / dashboard
-  (`GET /api/v1/cameras`, header `X-API-Key: changeme`). Status currently shows
-  `online:false` because no GoPro is attached on the bench (expected).
 - **GoPro Hero 3 protocol fix** (ESP-01S `fetchStatus` shutter bug) — required before
   real battery/recording data; needs a real Hero 3.
 - **Rotate the Gitea runner registration token** (was exposed in a setup paste).