Add WebDAV backup, statistics, progress and dashboard

- WebDAV uploader: concurrency, request and bandwidth limits, retry with
  backoff, offline catch-up, encrypted manifests, durability tracking
- Automatic unique remote directory claimed with a conditional PUT
- AES-256-GCM client-side encryption with keyed blob names
- /stats, /progress, /progress/stream and a /dashboard page
- Own ctypes inotify binding with a compact watch tree (263 MB -> 76 MB RSS)
- Directory-path ignore patterns and a forget command
- Indexed range queries instead of LIKE for path prefixes

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

tests/test_service.py

@@ -174,3 +174,15 @@ def test_restore_refuses_unsafe_paths(env):
     os.symlink("/etc", project / "escape")
     r = client.post(f"/api/v1/versions/{vid}/restore", json={"target_path": str(project / "escape" / "x")})
     assert r.status_code == 400
+
+
+def test_forget(env):
+    client, project = env
+    root = client.post("/api/v1/roots", json={"path": str(project)}).json()
+    wait_for(lambda: client.get(f"/api/v1/roots/{root['id']}").json()["baseline_state"] == "done")
+    dry = client.post("/api/v1/forget", json={"path": str(project / "src")}).json()
+    assert dry["dry_run"] and dry["files"] == 1 and dry["versions"] == 1
+    done = client.post("/api/v1/forget", json={"path": str(project / "src"), "dry_run": False}).json()
+    assert done["files_removed"] == 1 and done["blobs_removed"] == 1
+    assert history(client, project / "src" / "app.py") == []
+    assert history(client, project / "pyproject.toml")  # outside the forgotten tree