[Vinald]

Implements the full backlog from REVIEW.md plus repo housekeeping:

Identity

• Application/bundle ID renamed com.vinald.* → me.vinald.resumate (Android + iOS)
• Release APK now signed with a real upload keystore (android/key.properties, gitignored) instead of the debug key

Bug fixes (REVIEW.md)

• M3: signature images are decoded and re-encoded to real PNG on pick, with a try/catch guard around pw.MemoryImage as defense-in-depth
• L1: settings writes are debounced (~400ms) instead of firing per keystroke/slider frame
• L3: rename-dialog TextEditingController is now disposed
• L4: the PDF preview's page-format selector is now wired through to the renderer (was hardcoded to A4)
• L5: the LaTeX editor shows a banner that edits aren't saved back
• L7: export filenames are now collision-free and never empty

Dependencies

• intl, file_picker, share_plus, pdf_combiner bumped to their latest versions compatible with this project's Dart SDK constraint; migrated call sites to each package's new API
• Dropped the file_magic_number override — no longer needed by pdf_combiner 6.x
• pdf/printing/archive documented as blocked on a Dart SDK bump (their latest majors need >=3.12.0)

CI

• Added a debug APK build step so a real Android build break gets caught before main

Tests

• Added coverage for signature re-encoding and the resume editor's dirty-state flow (38 tests total, was 32)

Docs

• Consolidated CONTRIBUTING.md and docs/ARCHITECTURE.md into README.md; removed REVIEW.md (its items are now fixed or tracked as "Known limitations" in the README)
• Added an MIT LICENSE

Verified: flutter analyze clean, all 38 tests pass, and both flutter build apk --release and flutter build ios --release --no-codesign succeed end to end.