feat: Remove URL rewriting in favor of proper nextcloud config

Remove URL rewriting logic from MCP server that was converting
      public URLs to internal Docker URLs. This was a workaround for
      Nextcloud's overwritehost setting forcing URLs to localhost:8080.

      Changes:
      - Remove OIDC endpoint rewriting in app.py (setup_oauth_config)
      - Remove OIDC_JWKS_URI override support (no longer needed)
      - Remove URL rewriting in browser_oauth_routes.py
      - Remove URL rewriting in token_broker.py
      - Update Helm chart values and README
      - Add hybrid auth setup unit tests
      - Update Astrolabe admin UI for Vue 3

      The proper fix is in the previous commit which removes the
      overwritehost setting from Nextcloud, allowing it to respect
      the Host header from incoming requests.

third_party/astrolabe/src/components/admin/AdminSettings.vue

@@ -6,6 +6,12 @@
 			<p><strong>{{ t('astrolabe', 'Cannot connect to MCP server') }}</strong></p>
 			<p>{{ error }}</p>
 			<p class="help-text">{{ t('astrolabe', 'Ensure MCP server is running and accessible. Check config.php for correct mcp_server_url.') }}</p>
+			<NcButton type="primary" @click="retryConnection">
+				<template #icon>
+					<Refresh :size="20" />
+				</template>
+				{{ t('astrolabe', 'Retry Connection') }}
+			</NcButton>
 		</NcNoteCard>
 
 		<template v-else>
@@ -303,6 +309,13 @@ async function refreshStatus() {
 	showSuccess(t('astrolabe', 'Status refreshed'))
 }
 
+async function retryConnection() {
+	// Clear error and retry loading server status
+	error.value = null
+	loading.value = true
+	await loadServerStatus()
+}
+
 async function saveSettings() {
 	saving.value = true