Stop retaining detected manoeuvres; the CAM rate bump is their only consumer

The detector runs to raise the CAM transmit rate through a manoeuvre. Nothing
else read its output once the UI was removed, so keeping the rows was storing
data with no reader on the chance it would one day be analysed.

Drops the detected_events table in schema v5, deletes DetectedEventEntity and
the DAO and repository methods behind it, removes the insertEvent call from the
recording service, and removes the per-event rows and their five columns
(event_type, confidence, peak_accel, peak_gyro, duration_ms) from the trip CSV
along with the events parameter threaded through buildTripCsv and shareTripCsv.
A detected manoeuvre now lives for the length of one onDetectedEvent call.

MIGRATION_1_2 still creates the table: a v1 install upgrades 1-2-3-4-5 and so
creates it before v5 drops it. Removing it from the earlier migration would
break that path for anyone who has not upgraded yet.

trips.eventCount is kept. Dropping a SQLite column means recreating the table
and copying every recorded ride across, which is real risk for one unused
integer; the service still writes an accurate count and the CSV header still
reports it. It is the only thing left about detected manoeuvres.

This closes off the route to the false-positive measurement that 11.3 flags as
missing, so 11.3 now says that outright rather than pointing at an export that
no longer carries the data. Docs 11.3/11.4, the user guide, the README and the
traceability matrix updated to match. 55 tests, 0 failures.

README.md

@@ -38,7 +38,7 @@ Both paths converge at `CamUseCaseRepository`, which normalises whatever arrived
 
 **DENM transmission**; CiT One path only. Triggers the stationary vehicle profile (`hln-sv`, causeCode 94) via the consider it Use Case API. This is a manual antenna and range test tool. It is never triggered by a detected event or a use case alert, and the control is hidden entirely on the ESP32-C5 path.
 
-**Trip recording**; foreground service records all sensor streams and detects cycling manoeuvres (braking, turning, stopping) using orientation-independent signal processing. Works fully offline with no OBU connected. The detected manoeuvres are not shown in the app - they raise the CAM transmit rate through the manoeuvre on the ESP32-C5 path, and are kept in the trip's CSV export for offline analysis.
+**Trip recording**; foreground service records all sensor streams and detects cycling manoeuvres (braking, turning, stopping) using orientation-independent signal processing. Works fully offline with no OBU connected. The detected manoeuvres are neither shown nor stored - their only effect is to raise the CAM transmit rate through the manoeuvre on the ESP32-C5 path.
 
 **Trip review**; past trips displayed as a route on an OpenStreetMap layer, with duration and distance.