feat(astrolabe): add dynamic MCP server configuration for testing

Replace static post-installation configuration with dynamic test-time
configuration to support testing multiple MCP server deployments.

Changes:
- Remove static MCP server URL and OAuth client setup from post-installation
- Add configure_astrolabe_for_mcp_server fixture (session-scoped)
- Fixture dynamically configures:
  * Nextcloud system config (mcp_server_url, mcp_server_public_url)
  * OAuth client creation via occ oidc:create
  * Client credential storage (astrolabe_client_id, astrolabe_client_secret)
- Update existing OAuth tests to use dynamic configuration
- Add test_astrolabe_multi_server_integration.py with parametrized tests

Benefits:
- Test Astrolabe with mcp-oauth, mcp-keycloak, mcp-multi-user-basic
- Each test configures for its specific MCP server
- No static configuration conflicts between deployments
- Cleaner post-installation (37 lines, down from 85)

Test Results:
- test_astrolabe_configuration_for_different_servers: PASSED (mcp-oauth, mcp-keycloak)
- test_astrolabe_reconfiguration: PASSED

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

tests/server/oauth/test_nc_php_app_debug.py

@@ -10,8 +10,14 @@ logger = logging.getLogger(__name__)
 pytestmark = [pytest.mark.integration, pytest.mark.oauth]
 
 
-async def test_capture_settings_page(browser):
+async def test_capture_settings_page(browser, configure_astrolabe_for_mcp_server):
     """Capture what's actually rendered on the personal settings page."""
+    # Configure Astrolabe for mcp-oauth server
+    await configure_astrolabe_for_mcp_server(
+        mcp_server_internal_url="http://mcp-oauth:8001",
+        mcp_server_public_url="http://localhost:8001",
+    )
+
     nextcloud_host = os.getenv("NEXTCLOUD_HOST", "http://localhost:8080")
     username = os.getenv("NEXTCLOUD_USERNAME", "admin")
     password = os.getenv("NEXTCLOUD_PASSWORD", "admin")