feat(error-handling): add network error differentiation, retry, and REST API detection (C.5)

WordPress client improvements:
- Add ConnectionError exception for network-level failures
- Differentiate DNS, SSL, timeout, and connection refused errors
- Add retry with exponential backoff for transient errors (502, 503, 504, 429)
- Auth/config errors are never retried
- Add request timeout (30s default)

Health check improvements:
- Detect REST API disabled (403/404 on /wp-json)
- Classify errors by type: dns_failure, ssl_error, timeout, connection_refused

Bare except cleanup:
- Replaced all bare except: with except Exception: across 12 files

Tests: 303 passed (13 new tests for error handling)

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

plugins/openpanel/handlers/profiles.py

@@ -236,8 +236,8 @@ async def get_profile(client: OpenPanelClient, project_id: str, profile_id: str)
                     indent=2,
                     ensure_ascii=False,
                 )
-        except:
-            pass
+        except Exception:
+            pass  # Profile event fetch is optional; fall through to generic response
 
         return json.dumps(
             {