T27: parity audit and handover

PARITY-AUDIT.md walks every row of the v2.0.1 feature table with the evidence
behind each claim, keeping verified, implemented-but-unproven, and gap strictly
apart rather than ticking boxes in bulk.

Carried the durable docs forward: ARCHITECTURE.md with what changed and why,
a README covering status and the parity harness, and the v3 backlog with a
header noting the two items whose status changed. The native repo's README now
opens with a pointer here and records both bugs the port found. All internal
doc links verified.

The cutover step is deliberately left undone: the application id stays
com.rippr.port so both apps can be installed together, because the real-ride
checklist depends on recording the same ride on both at once. That comparison is
worth more than finishing tidily. The native repo is marked superseded rather
than archived -- it is still the only version that has recorded a real ride.

Also corrected an arithmetic slip: 175 tests, not 178.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/port/PROGRESS.md

@@ -736,4 +736,64 @@ build, and a demo video for the review notes.
 
 **T22, T23, T24 complete. T25 and T26 need a real device and a real rider.**
 
-`178 tests passing` (171 unit + widget, plus 4 integration on device), analyze clean.
+`175 tests passing` — 171 unit and widget, plus 4 integration on device. Analyze clean.
+
+> Corrected: an earlier summary in this file said 178. 171 + 4 is 175.
+
+---
+
+## T27 — Parity audit and handover · **complete, except the cutover step**
+
+[PARITY-AUDIT.md](PARITY-AUDIT.md) walks every row of the v2.0.1 feature table with the
+evidence behind each claim, keeping three categories strictly apart: **verified** (a test
+asserts it, or it ran on a device), **implemented but unproven**, and **gap**.
+
+Deliberately not ticked in bulk — a v2 task once had every criterion checked by a blanket
+regex including unverified items, and that lesson is written into the audit's preamble.
+
+### Documentation carried forward
+
+- `docs/ARCHITECTURE.md` — the durable reasoning, with a table of what changed and why,
+  the Float→double divergence, and the two iOS settings that are easy to get wrong
+- `README.md` — status, the parity harness, and the two native bugs this port found
+- `docs/V3-BACKLOG.md` — carried over with a header noting the two items whose status
+  changed (UI tests are no longer a gap; elevation can now be checked against Kotlin)
+- The native repo's `README.md` now opens with a pointer here, and records both bugs
+
+All internal documentation links verified to resolve.
+
+### The cutover step is deliberately NOT done
+
+**The application id stays `com.rippr.port`.**
+
+Switching it to `com.rippr` is the last act of the port, but doing it now would stop the
+two apps coexisting — and `REAL-RIDE-CHECKLIST.md` item **A3** depends on recording the
+same ride on both simultaneously. That side-by-side comparison is the strongest evidence
+available that the port is faithful, and it is worth more than finishing the checklist
+tidily.
+
+The native repo is therefore marked **superseded, not archived**: it is still the only
+version that has recorded a real ride.
+
+### An arithmetic correction
+
+An earlier entry in this file said 178 tests. The real figure is **175** — 171 unit and
+widget, plus 4 integration. Corrected in place.
+
+---
+
+## The port is complete
+
+| | |
+|---|---|
+| **175 tests** | 171 unit and widget, 4 integration on a real iOS simulator |
+| **~4,600 lines** of Dart | plus 3,000 generated by Drift |
+| **Both platforms build** | and the app runs on an iOS simulator |
+| **Analyze clean** | throughout |
+| **Parity proven, not assumed** | `tool/parity/run.sh` diffs against the real Kotlin |
+
+Two bugs found in the native app. One capability lost (notification actions). The first UI
+tests the project has ever had.
+
+**What remains is not code.** It is a rider, two phones, and
+[REAL-RIDE-CHECKLIST.md](REAL-RIDE-CHECKLIST.md).