fix(ci): move setup-java after android project generation

[acamarata]

Summary

Follow-up to #157 (bumps actions/setup-java@v5 -> @v6). That PR's checks
are green but misleading: every job that runs setup-java is skipped on a
normal PR (build-capacitor.yml / build-react-native.yml are
workflow_dispatch-only; deploy-mobile-android.yml is tag-triggered). These
workflows have never run on main.

Dispatching them directly against #157's branch, both failed at the Setup
Java step:

No file in /home/runner/work/nchat/nchat matched to
[**/*.gradle*,**/gradle.properties,**/gradle-wrapper.properties, ...],
make sure you have checked out the target repository

Cause: cache: 'gradle' in actions/setup-java needs gradle files to key
its cache on. In v5 a miss was a warning; in v6 it's a hard job failure. The
native android/ project in this repo is gitignored and generated at build
time (npx cap add android / capacitor sync), so on a fresh checkout no
gradle files exist until that generation step runs. All three workflows ran
Setup Java before that step.

Changes

• build-capacitor.yml: move Setup Java to after Add + Sync Capacitor Android
• build-react-native.yml: move Setup Java to after Install dependencies (which generates the native project)
• deploy-mobile-android.yml: move Setup Java to after Sync Capacitor
• All three now also set cache-dependency-path so the gradle cache keys correctly once the files exist

ci.yml already had this exact fix (with an explanatory comment) from an
earlier change — these three workflows follow the same pattern.

actions/setup-java@v6 is kept, not reverted.

Verification

Dispatched both build-capacitor.yml and build-react-native.yml directly
against this branch:

• build-react-native.yml (run 33085534559): fails at Install dependencies
  ("No such file or directory") — pre-existing, unrelated:
  frontend/platforms/react-native does not exist in this repo (not in
  pnpm-workspace.yaml, no tracked files). The React Native platform was
  never scaffolded. Setup Java never reaches execution because of this
  earlier failure; this is unrelated to the setup-java ordering fix and out
  of scope here.
• build-capacitor.yml (run 33085531501): fails earlier, at Build web assets (HASURA_ADMIN_SECRET must be set for production builds - the
  workflow's pnpm build step never passes that secret through, another
  pre-existing gap unrelated to setup-java).

To isolate and prove the actual fix, I ran a disposable local-only
verification (never pushed as part of this PR) that patched around those two
unrelated pre-existing gaps (passed HASURA_ADMIN_SECRET through, added the
missing mobile vite build step that ci.yml already has). With those
workarounds, the real fix in this PR was exercised end-to-end:

Build web assets: success
Add + Sync Capacitor Android: success
Setup Java: success          <- the actual fix, proven
Build Android (Debug): success
Upload Android artifact: success

Full job: https://github.com/nself-org/nchat/actions/runs/33086902029

Test plan

• YAML syntax validated for all three changed files
• Dispatched build-capacitor.yml and build-react-native.yml against this branch
• Confirmed Setup Java itself succeeds once ordered after android project generation (isolated verification run)
• build-react-native.yml needs its own fix to scaffold frontend/platforms/react-native before it can be exercised for real (separate, pre-existing issue, not addressed here)
• build-capacitor.yml's production workflow needs HASURA_ADMIN_SECRET wired into the Build web assets step (separate, pre-existing issue, not addressed here)

[github-actions]

PR Checks Summary

Check	Status
Lint & Format	⏭️ skipped
Type Check	⏭️ skipped
Unit Tests	⏭️ skipped
Build	⏭️ skipped

---

✅ All checks passed! Ready for review.

[github-actions]

Security Scan Results: PASSED

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