feat(android): Projects/Diff/Worktree/git-write parity with web+iOS (W5)

Brings the native Android client to parity with the web/iOS Projects + git surface,
consuming the existing server endpoints — ZERO server change. (The "SDK-gated modules"
premise was stale; they were already online.)

- :api-client (pure Kotlin/JVM): PrStatus/GitLog/GitWrite models (tolerant decoders,
  safe-error), ProjectInfo + ahead/behind/lastCommitMs; 8 new Endpoints builders
  (projectPr/projectLog read-only; createWorktree/removeWorktree/prune/gitStage/
  gitCommit/gitPush guarded w/ Origin) + ApiClient methods (PR/log degrade in body;
  writes 200→Ok / 429→RateLimited / 4xx-5xx→Rejected(safe msg)).
- :app presenters (JVM-tested): DiffViewModel base-compare + git stage/commit/push;
  new WorktreeViewModel (create/remove/prune + client branch validation + isMain block);
  ProjectDetailViewModel failure-isolated PR-chip + recent-commits.
- Compose screens wired: ProjectDetail (PR chip tappable only for https, recent commits,
  worktree create/remove-with-force/prune, view-diff), Diff (base input, per-file
  stage/unstage, commit/push bar), Projects (ahead/behind sync chip). Nav closes the
  pre-existing "no inbound link to the diff screen" gap.

Verified independently: `./gradlew :app:assembleDebug test :api-client:koverVerify`
BUILD SUCCESSFUL; 348 unit tests pass (api-client 102 / app 246); coverage gate held;
git status android-only. Compose rendering/interaction deferred to on-device QA
(android/DEVICE_QA_CHECKLIST.md), as prior Android waves did.

android/DEVICE_QA_CHECKLIST.md

@@ -66,6 +66,25 @@ Kover ≥80% on the pure modules); this checklist is what a human runs on real h
 - [ ] adaptive: compact = stack, expanded/tablet = list+detail (`NavigationSuiteScaffold` +
       `ListDetailPaneScaffold`); pointer secondary-click context menu on a tablet (sw≥600).
 
+## Projects / git parity (W5 — presenters JVM-tested, Compose device-QA)
+- [ ] Project card **sync chip**: `↑ahead` / `↓behind` render only when non-zero; no chip when there is
+      no upstream (fields absent).
+- [ ] Project detail **PR chip**: `availability=ok` → tappable chip opens the PR in the browser ONLY when
+      the url is https (a non-https / junk url is inert, non-clickable); `no-pr` / `not-installed` /
+      `unauthenticated` / `disabled` / `error` each render the degraded copy inertly; check-count colour
+      (fail=red / pending=amber / pass=green).
+- [ ] Project detail **recent commits**: list renders short-hash + subject inertly; unavailable state on a
+      log failure does NOT hide the rest of the detail (failure-isolated).
+- [ ] **New worktree** inline form: valid `branch` (+optional `base`) → create → list refreshes; an invalid
+      branch name is rejected with NO network call; a disabled-403 shows the server's safe message.
+- [ ] Per-worktree **remove**: the button is absent on the `main` worktree; the confirm dialog offers a
+      **Force** checkbox; a dirty-worktree 409 surfaces "force required" inertly; **prune** button works.
+- [ ] Diff **base-rev** input: entering a rev enters base mode (Working/Staged toggle hidden, `vs <rev>`
+      shown, git-write controls hidden); Clear returns to working/staged; junk rev → server 400 surfaced.
+- [ ] Diff **stage/unstage**: per-file button (Working→"暂存", Staged→"取消暂存") posts the file and
+      refreshes; **commit** field + button (empty message rejected client-side; Ok shows the short sha) ;
+      **push** button (Ok shows branch→remote; 409 shows the inert server message; 429 shows rate-limited).
+
 ## Known minor gaps (tracked, non-blocking — see PROGRESS_ANDROID.md)
 - [ ] push body-tap opens the app (not yet the specific gate — the notification `openAppIntent` doesn't
       carry the sessionId; the gate is still visible in the terminal). MEDIUM.