feat: add admin/profile UI, i18n (fr/de/pt), fix CI pipelines

- Add admin panel link and profile modal in user menu dropdown
- Add French, German and Portuguese locale support (full translations)
- Register new locales across JS frontend and Rust backend
- Create CI pipeline (fmt, clippy, test, audit, build)
- Fix docker-build.yml (cache, real tests, reduced timeout)
- Fix docker-publish.yml (multi-arch via QEMU, latest tag, pre-publish tests)
- Add dependabot.yml for automated dependency updates

.github/dependabot.yml

@@ -0,0 +1,40 @@
+version: 2
+updates:
+  # Rust (Cargo) dependencies
+  - package-ecosystem: "cargo"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+      day: "monday"
+    open-pull-requests-limit: 10
+    labels:
+      - "dependencies"
+      - "rust"
+    commit-message:
+      prefix: "deps(rust):"
+
+  # GitHub Actions
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+      day: "monday"
+    open-pull-requests-limit: 5
+    labels:
+      - "dependencies"
+      - "ci"
+    commit-message:
+      prefix: "deps(ci):"
+
+  # Docker
+  - package-ecosystem: "docker"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+      day: "monday"
+    open-pull-requests-limit: 3
+    labels:
+      - "dependencies"
+      - "docker"
+    commit-message:
+      prefix: "deps(docker):"