feat(httpmw): initial stable release v0.9.0

Standalone net/http middleware for panic recovery, CORS, request ID injection, and request logging.

What's included:
- Recover(): panic -> 500, captures debug.Stack, no logger required
- CORS(origins): OPTIONS 204 preflight, origin allowlist, package-wide method/header constants
- RequestID(generator): injects ID via logz.WithRequestID, sets X-Request-ID response header
- RequestLogger(logger): logs method/path/status/latency/request_id; Error for 5xx, Info otherwise
- Logger interface: Info, Error, With — duck-typed; satisfied by logz.Logger
- StatusRecorder: exported http.ResponseWriter wrapper that captures written status code
- Direct logz import for context helpers (documented exception to ADR-001)

Tested-via: todo-api POC integration
Reviewed-against: docs/adr/

doc.go

@@ -0,0 +1,5 @@
+// Package httpmw provides stdlib net/http middleware for transport concerns:
+// panic recovery, CORS, request ID injection, and structured request logging.
+//
+// No authentication or identity logic lives here — see httpauth-firebase for that.
+package httpmw