feat: implement T05, T08, T13 — OIDC discovery, JWKS, telemetry pipeline

- T05: /.well-known/openid-configuration — profile-only features advertised
- T08: /jwks — RS256 JWK Set, stdlib crypto only, key rotation support
- T13: Structured telemetry — Event types, LogEmitter/NoopEmitter/MultiEmitter, context helpers

38 server tests pass, go vet clean.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/go.mod

@@ -2,4 +2,13 @@ module keycape
 
 go 1.22
 
-require gopkg.in/yaml.v3 v3.0.1
+require (
+	github.com/rs/zerolog v1.34.0
+	gopkg.in/yaml.v3 v3.0.1
+)
+
+require (
+	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-isatty v0.0.19 // indirect
+	golang.org/x/sys v0.12.0 // indirect
+)