feat(reverb): Channel types, BroadcastEvent, auth registry, Broadcaster, ReverbProvider

[bedus-creation]

Summary

Implements tasks #147, #148, and #149 — the full Reverb broadcasting core module under fastapi_startkit/src/fastapi_startkit/reverb/.

Task #147 — BroadcastEvent + Channel types (reverb/channels.py, reverb/event.py)

• Channel — public channel, no auth check; __eq__/__hash__ for easy comparison in tests
• PrivateChannel — automatically prefixes name with private-; stores _raw_name
• PresenceChannel — automatically prefixes name with presence-; stores _raw_name (member tracking is v2)
• BroadcastEvent — abstract base with payload: dict, name: str | None (defaults to class.__name__ at dispatch time), abstract broadcast_on(), and async emit() shortcut that delegates to Broadcast.dispatch(self)

Task #148 — Broadcast facade + auth registry (reverb/registry.py, reverb/broadcaster.py, facades/Broadcast.pyi)

• ChannelAuthRegistry — compiles orders.{order_id} patterns to named-group regexes; strips private-/presence- prefix before matching; casts wildcard values to callback type hints; supports both sync and async callbacks; default policy: deny private/presence, allow public
• Broadcaster — bound as "broadcast" and "reverb" in the container:
  • dispatch(event) — primary path, resolves event.name, iterates broadcast_on() channels
  • emit(channel, event_name, payload) — escape hatch for dynamic one-off broadcasts
  • channel(pattern) — decorator factory that registers auth callbacks in the registry
• facades/Broadcast.pyi — updated type stub with dispatch(), emit(), channel() signatures

Task #149 — ReverbProvider (reverb/provider.py)

• register() — creates ReverbServer, ChannelAuthRegistry, Broadcaster; binds all under "reverb", "broadcast", "reverb.server", "reverb.registry"
• boot() — auto-loads routes/channels.py via importlib (silent skip if absent or erroring); mounts WebSocket at REVERB_PATH (default /__reverb); mounts POST /broadcasting/auth supporting both form-encoded and JSON bodies, returning 200 {"auth": "..."} or 403 {"message": "Forbidden"}

Test plan

• All 31 existing tests/broadcasting/ tests pass unchanged
• 1262 non-Postgres tests pass (15 Postgres failures are pre-existing/require a live DB)
• Manual smoke test: channel types, registry pattern matching + type casting, async/sync callbacks, Broadcaster dispatch/emit/channel decorator

🤖 Generated with Claude Code

[bedus-creation]

Review — Superseded by PR #112 (close this PR)

Thank you for the implementation! This PR contains a well-designed reverb/ package with some excellent ideas. However, per the architecture decision, the canonical implementation lives in the existing broadcasting/ package (PR #112, feat/broadcasting-event-facade-provider), not a new parallel reverb/ module.

Conflicts with agreed architecture

Issue	Detail
New top-level reverb/ package	Contradicts the course-correction directive to extend broadcasting/
Container key "broadcast"	PR #112 uses "broadcasting" — inconsistency breaks the Broadcast facade
Import paths fastapi_startkit.reverb.*	Would require all user code to use different imports than the rest of the broadcasting module

Good ideas from this PR cherry-picked into #112

The following ideas from #116 are valuable and have been flagged for inclusion in PR #112:

1. __eq__ / __hash__ on Channel — makes channels comparable and hashable (sets, dict keys)
2. async def emit(self) — correctly awaits Broadcast.dispatch(self) (PR feat(broadcasting): BroadcastEvent.emit(), Broadcast facade, ChannelAuthRegistry, ReverbProvider auto-wiring #112 has a bug here — emit() is not async, so events are silently dropped)
3. Prefix stripping in registry — _strip_prefix() so callbacks can match "orders.{id}" instead of "private-orders.{id}" (ergonomic improvement)

Recommendation: Close this PR and let PR #112 (once the blocking issues are fixed) be the merge target. The good ideas above are being tracked as required fixes on #112.

[bedus-creation]

Superseded by merged PR #112 — broadcasting/ extension chosen over parallel reverb/ package; its async-emit and Channel equality improvements were ported into #112 before merge.