fix(config): correct OIDC token-type/scopes env keys; address review round 1

- _DEFAULTS keys for NEXTCLOUD_OIDC_TOKEN_TYPE / NEXTCLOUD_OIDC_SCOPES were
  registered as oidc_* (uppercasing to OIDC_*), so dynaconf
  (ignore_unknown_envvars) never read the NEXTCLOUD_-prefixed env vars and the
  fields stayed at their defaults. Prefix the keys to match _field_map; add a
  regression test.
- Add gte=1 validator for HEALTH_READY_REFRESH_INTERVAL and a 1..65535 range
  validator for PORT.
- Tie ReadinessCache.ttl_seconds to 2x the configured refresh interval so
  is_stale() stays meaningful when the interval is tuned.
- Raise the refresh-loop exception log from DEBUG to WARNING.
- Make health_ready a sync handler (no awaits); dedupe the localhost fallback
  into _DEFAULT_MCP_SERVER_URL; use pytest.approx for the float default.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

nextcloud_mcp_server/config.py

@@ -37,8 +37,10 @@ _DEFAULTS: dict[str, Any] = {
     "cookie_secure": None,
     # OAuth/OIDC
     "oidc_discovery_url": None,
-    "oidc_token_type": "Bearer",
-    "oidc_scopes": "",
+    # Keys must uppercase to the env var dynaconf reads (ignore_unknown_envvars):
+    # NEXTCLOUD_OIDC_TOKEN_TYPE / NEXTCLOUD_OIDC_SCOPES, matching _field_map.
+    "nextcloud_oidc_token_type": "Bearer",
+    "nextcloud_oidc_scopes": "",
     "port": 8000,
     "nextcloud_oidc_client_id": None,
     "nextcloud_oidc_client_secret": None,
@@ -312,6 +314,8 @@ _dynaconf = Dynaconf(
         Validator("VECTOR_SYNC_QUEUE_MAX_SIZE", gte=1),
         Validator("VECTOR_SYNC_METRICS_REFRESH_INTERVAL", gte=1),
         Validator("VECTOR_SYNC_USER_POLL_INTERVAL", gte=1),
+        Validator("HEALTH_READY_REFRESH_INTERVAL", gte=1),
+        Validator("PORT", gte=1, lte=65535),
         Validator("VERIFICATION_CONCURRENCY", gte=1),
         Validator("DOCUMENT_CHUNK_SIZE", gte=1),
         Validator("DOCUMENT_PARSE_TIMEOUT_SECONDS", gte=1),