feat: Intervals.icu MCP portal (FastAPI + Authentik OIDC)

- OIDC login via Authentik; first login creates a disabled user (admin approval).
- Users set/replace their Intervals.icu athlete ID + API key; the key is validated
  against Intervals.icu and stored AES-256-GCM encrypted (shared key with the MCP
  server). Same users table (schema owned by the MCP server's migrations).
- Admin page (gated on the intervalsicu-mcp-admins group claim): list, approve,
  disable, delete users.
- 29 tests @ 93% (OIDC routes integration-only); Dockerfile asserts templates are
  packaged; .gitea CI test-gates the image build.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitea/workflows/build.yaml

@@ -0,0 +1,42 @@
+name: build-image
+
+on:
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+      - name: Install (editable, with dev extras)
+        run: pip install --quiet -e ".[dev]"
+      - name: Test + coverage gate
+        run: pytest
+
+  build:
+    needs: test
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    env:
+      IMAGE: git.farh.net/farhoodlabs/intervalsicu-mcp-ui
+      DOCKER_BUILDKIT: "1"
+    steps:
+      - uses: actions/checkout@v4
+      - name: Login to registry
+        run: echo "${{ secrets.REGISTRY_TOKEN }}" | docker login git.farh.net -u cpfarhood --password-stdin
+      - name: Build image
+        run: docker build --progress=plain -t "${IMAGE}:latest" -t "${IMAGE}:${GITHUB_SHA}" .
+      - name: Push image
+        run: |
+          docker push "${IMAGE}:latest"
+          docker push "${IMAGE}:${GITHUB_SHA}"