Add src/server/auth.rs with bearer_auth_middleware axum layer that
extracts the Authorization: Bearer header, resolves via
IdentityProvider::resolve_from_token, and stashes Option<Identity> in
request extensions. Shared by HTTP gateway routes and the to_mcp rmcp
service (research §4.4). No token, malformed header, or failed
resolution all yield None (unauthenticated, not an error) — Bearer-only
auth mechanism (ADR-004).
Includes ResolvedIdentity axum extractor reading from extensions, and
wires the middleware into the HttpAdapter router around the
gateway/openapi/mcp routes (excluding the raw /healthz route).
glm-5.2
36f74dd31b