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/wordpress/handlers/menus.py

@@ -190,7 +190,7 @@ class MenusHandler:
             # Try custom endpoint first, fallback to standard if not available
             try:
                 menus = await self.client.get("menus", use_custom_namespace=True)
-            except:
+            except Exception:
                 # Fallback: use wp/v2/navigation endpoint (WP 5.9+)
                 menus = await self.client.get("navigation")
 
@@ -216,7 +216,7 @@ class MenusHandler:
             # Get menu details
             try:
                 menu = await self.client.get(f"menus/{menu_id}", use_custom_namespace=True)
-            except:
+            except Exception:
                 menu = await self.client.get(f"navigation/{menu_id}")
 
             # Get menu items
@@ -256,7 +256,7 @@ class MenusHandler:
 
             try:
                 menu = await self.client.post("menus", json_data=data, use_custom_namespace=True)
-            except:
+            except Exception:
                 # Try navigation endpoint
                 menu = await self.client.post("navigation", json_data=data)