NE Hub: Seafile, OnlyOffice, Plex, calendar and mail in one PWA

- Mobile-first PWA (phone tab bar with More menu, iPad/desktop rail)
- Passkey (WebAuthn) sign-in gates the whole app; first passkey via setup code
- Files: Seafile browse/upload/new doc/rename/move/share link/preview/delete
- In-app OnlyOffice editing with JWT-signed configs and save-back to Seafile
- Plex music player via plex.tv sign-in and a server-side proxy
- Calendar agenda from private ICS links (recurrence + time zones)
- Search, Home dashboard, webmail deep links, audiobooks frame
- Dockerfile, compose, and a Gitea Actions workflow that builds the image

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

.gitea/workflows/build.yml

@@ -0,0 +1,44 @@
+name: build-container
+
+on:
+  push:
+    branches: [main]
+    tags: ['v*']
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: docker/setup-qemu-action@v3
+      - uses: docker/setup-buildx-action@v3
+
+      # Repo secrets needed (Settings -> Actions -> Secrets):
+      #   REGISTRY_TOKEN  a Gitea access token with write:package scope
+      #   REGISTRY_USER   optional; defaults to the user who pushed
+      - uses: docker/login-action@v3
+        with:
+          registry: git.necloud.us
+          username: ${{ secrets.REGISTRY_USER || gitea.actor }}
+          password: ${{ secrets.REGISTRY_TOKEN }}
+
+      - id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: git.necloud.us/nate/hub
+          tags: |
+            type=raw,value=latest,enable={{is_default_branch}}
+            type=sha,format=short
+            type=ref,event=tag
+
+      - uses: docker/build-push-action@v6
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=registry,ref=git.necloud.us/nate/hub:buildcache
+          cache-to: type=registry,ref=git.necloud.us/nate/hub:buildcache,mode=max