chore(ci): migrate workflows to gitea + consolidate keystore secret

- rename .forgejo/workflows/ to .gitea/workflows/ (git mv preserves
  history); Gitea Actions reads either path, but the directory now
  matches the active platform
- collapse ANDROID_STORE_PASSWORD + ANDROID_KEY_PASSWORD into a
  single ANDROID_KEYSTORE_PASSWORD secret (PKCS12 keystores require
  the two passwords to be identical, so the duplication carried no
  information); build.gradle.kts still reads two env vars to stay
  format-agnostic, both now sourced from the same secret in CI
- ignore android/*.keystore, android/*.keystore.*, android/*.jks,
  android/keystore.properties so the regenerated signing material
  never reaches a remote on accident
- update prose references from Forgejo to Gitea in CLAUDE.md and
  the docs; the historical "migrated from Forgejo" note in CLAUDE.md
  is kept intentionally; forgejo/upload-artifact@v3 action refs are
  left untouched (canonical artifact action, resolves cleanly under
  Gitea Actions)

Operator side: ANDROID_KEY_ALIAS, ANDROID_KEYSTORE_PASSWORD, and
ANDROID_KEYSTORE_B64 secrets registered in Gitea before this lands.

.gitea/workflows/test-web.yml

@@ -0,0 +1,40 @@
+name: test-web
+
+# Web SPA: vitest + svelte-check. Runs on push to dev/main and PRs to
+# main, scoped to web/** changes only — Go-only or Flutter-only diffs
+# don't trigger this workflow.
+
+on:
+  push:
+    branches: [dev, main]
+    paths:
+      - 'web/**'
+      - '.gitea/workflows/test-web.yml'
+  pull_request:
+    branches: [main]
+    paths:
+      - 'web/**'
+      - '.gitea/workflows/test-web.yml'
+
+jobs:
+  test:
+    runs-on: go-ci
+    container:
+      image: git.fabledsword.com/bvandeusen/ci-go:1.26
+
+    defaults:
+      run:
+        working-directory: web
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install deps
+        run: npm ci
+
+      - name: Type-check + svelte-check
+        run: npm run check
+
+      - name: Vitest
+        run: npm test