feat: initial scaffold of CrowdSec admin webapp

Flask + htmx mini-app to list and delete CrowdSec decisions from a browser,
gated behind Authentik. Talks to host LAPI via host.docker.internal:8080
using machine JWT auth (bouncer X-Api-Key is read-only).

Gitea Actions CI/CD on push to main: runner rebuilds image and brings the
stack up via docker compose on the host (same pattern as flight-radar).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.gitignore

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+.env
+__pycache__/
+*.pyc
+*.pyo
+.venv/
+.vscode/
+.idea/