Refresh the Flutter snapshot: v3 tickets V3-04 through V3-16, plus a fresh installable APK

V3-04 through V3-07, V3-10, V3-16 shipped complete; V3-11/V3-12/V3-14 shipped code-complete pending device/account verification; V3-08/V3-09 deferred behind a new V3-17 (self-hosted OSRM investigation). 316 tests passing, up from 221.

The APK is a fresh release build (debug-signed, no release signing config exists yet) with two build fixes applied: core library desugaring enabled for flutter_local_notifications, and sentry_flutter bumped to 9.27.0 (8.14.2's bundled Kotlin plugin was incompatible with this project's Kotlin 2.4.0 toolchain).

rippr-flutter-src/docs/v3/V3-13-real-ride-measurements.md

@@ -0,0 +1,61 @@
+# V3-13 — Real-ride measurements: elevation, battery, map lifecycle
+
+**Phase** Quality · **Depends on** the real-ride checklist · **Size** M · **Status** Blocked on riding
+
+## Goal
+Answer three questions that no amount of code can answer, then act on the answers.
+
+## Context
+Three items have been carried since v2 because **nothing but a real ride settles them**.
+Grouped into one ticket because they share a prerequisite: riding, with instruments.
+
+## The three questions
+
+### 1. Is elevation gain actually wrong?
+~30 m of phantom gain per ten stationary minutes against **synthetic ±8 m uniform noise**.
+Real GPS altitude error is *correlated* — it wanders rather than jitters — so the true
+behaviour is unknown.
+
+**Do not tune this blind.** Record a flat ride and see what it reports. Only then consider
+a longer smoothing window, a larger threshold, or the barometer — which most phones have
+and which is far more accurate than GPS altitude.
+
+The port has an advantage the native app did not: `tool/parity/run.sh` proves the algorithm
+is bit-identical to the Kotlin original, so any change can be measured against a known
+baseline rather than guessed at.
+
+### 2. What does it actually cost in battery?
+Never measured, on either app. And V3-04/V3-05 make it worse: a lit screen and continuous
+map rendering are a different order of cost from a background service.
+
+Measure three configurations over a multi-hour ride: pocketed with no map, pocketed with
+the live map on, and mounted with the screen awake.
+
+### 3. Does the map leak?
+`flutter_map`'s lifecycle was wired carefully but never leak-tested across repeated
+navigation. The native repo flagged the osmdroid equivalent as a known hazard.
+
+## Implementation
+1. Run the checklist in [../port/REAL-RIDE-CHECKLIST.md](../port/REAL-RIDE-CHECKLIST.md)
+2. Record elevation on a known-flat route; compare against a barometric or surveyed source
+3. Battery: note the percentage at start and end for each configuration, with duration
+4. Memory: navigate rides → detail → back fifty times with DevTools attached, watching
+   for monotonic growth
+5. **Write the numbers into this file.** The point is a record, not a vibe.
+
+## Acceptance criteria
+- [ ] Flat-ride elevation gain recorded, with a verdict: acceptable or not
+- [ ] Battery cost per hour recorded for all three configurations
+- [ ] Memory across fifty navigations recorded, with a leak verdict
+- [ ] Any resulting code change is justified by a number written down here
+
+## Tests
+Measurement, not tests. Any fix that follows gets its own regression test, and elevation
+changes must be re-checked against the parity harness.
+
+## Risks
+The temptation to tune elevation on a hunch. The v2 backlog says do not, twice, and the
+existing bound was already shown to pass on seed luck.
+
+## Out of scope
+Fixes themselves. This ticket produces evidence; the fixes are separate work.