feat: auto-update (download+auto-install) + tide numbers (v0.6.0)

Auto-update, autoGPS-style, ported to a Capacitor native plugin:
- UpdaterPlugin.java: downloadAndInstall(url) streams the APK to cacheDir
  emitting a 'progress' event per percent, then fires the FileProvider
  install intent (application/vnd.android.package-archive). canInstall()/
  openInstallSettings() handle the Android 8+ unknown-sources permission.
- MainActivity registers the plugin; manifest gains REQUEST_INSTALL_PACKAGES
  (FileProvider + cache file_paths already present).
- UpdateBanner: "업데이트" now shows a shimmer progress bar with live percent
  and auto-installs on completion; falls back to Browser.open on web and
  prompts for the install permission when missing. Mandatory modal keeps
  update/exit.

Tide numbers (user asked for 만조/간조/조차 수치):
- Timeline badges show ▲/▼ change (delta) for every event, absolute cm for
  official stations; Today shows "오늘 조차 NNNcm". Model spots show change/
  range (datum-independent) marked 예측.

Verified: gradle assembleDebug compiles the native plugin; Playwright shows
군산 with 조차 497cm, 만조 06:37 630cm ▲497, 간조 13:18 200cm ▼430. Deployed v0.6.0.

Constraint: APK auto-install needs the user to grant unknown-sources once; the plugin detects this and opens the settings screen rather than failing silently.
Confidence: medium
Scope-risk: module
Reversibility: moderate
Directive: Real-device test the full download->install flow (permission grant, installer dialog) — cannot be verified in CI/web.
Tested: gradle build (plugin compiles); app build clean; web fallback path; tide-number rendering via Playwright.
Not-tested: on-device download progress + install intent + unknown-sources permission round-trip (needs a phone).
Related: docs/BACKLOG.md

🐙 Autopus <noreply@autopus.co>