fix: resolve all 301 error handling anti-patterns across codebase

Systematic cleanup of every error handling anti-pattern detected by the
automated scanner. 289 issues fixed via code changes, 12 approved with
specific technical justifications.

Changes across 90 files:
- GENERIC_CATCH (141): Added instanceof Error type discrimination
- LARGE_TRY_BLOCK (82): Extracted helper methods to narrow try scope to ≤10 lines
- NO_LOGGING_IN_CATCH (65): Added logger/console calls for error visibility
- CATCH_AND_CONTINUE_CRITICAL_PATH (10): Added throw/return or approved overrides
- ERROR_STRING_MATCHING (2): Approved with rationale (no typed error classes)
- ERROR_MESSAGE_GUESSING (1): Replaced chained .includes() with documented pattern array
- PROMISE_CATCH_NO_LOGGING (1): Added logging to .catch() handler

Also fixes a detector bug where nested try/catch inside a catch block
corrupted brace-depth tracking, causing false positives.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/services/sync/ChromaMcpManager.ts

@@ -78,6 +78,11 @@ export class ChromaMcpManager {
       await this.connecting;
     } catch (error) {
       this.lastConnectionFailureTimestamp = Date.now();
+      if (error instanceof Error) {
+        logger.error('CHROMA_MCP', 'Connection attempt failed', {}, error);
+      } else {
+        logger.error('CHROMA_MCP', 'Connection attempt failed with non-Error value', { error: String(error) });
+      }
       throw error;
     } finally {
       this.connecting = null;
@@ -307,9 +312,15 @@ export class ChromaMcpManager {
     // Try JSON parse first; if it fails, return the raw text for non-error responses.
     try {
       return JSON.parse(firstTextContent.text);
-    } catch {
+    } catch (parseError: unknown) {
       // Plain text response (e.g. "Successfully created collection cm__foo")
       // Return null for void-like success messages, callers don't need the text
+      if (parseError instanceof Error) {
+        logger.debug('CHROMA_MCP', 'Non-JSON response from tool, returning null', {
+          toolName,
+          textPreview: firstTextContent.text.slice(0, 100)
+        });
+      }
       return null;
     }
   }
@@ -322,7 +333,10 @@ export class ChromaMcpManager {
     try {
       await this.callTool('chroma_list_collections', { limit: 1 });
       return true;
-    } catch {
+    } catch (error) {
+      logger.warn('CHROMA_MCP', 'Health check failed', {
+        error: error instanceof Error ? error.message : String(error)
+      });
       return false;
     }
   }
@@ -342,7 +356,11 @@ export class ChromaMcpManager {
     try {
       await this.client.close();
     } catch (error) {
-      logger.debug('CHROMA_MCP', 'Error during client close (subprocess may already be dead)', {}, error as Error);
+      if (error instanceof Error) {
+        logger.debug('CHROMA_MCP', 'Error during client close (subprocess may already be dead)', {}, error);
+      } else {
+        logger.debug('CHROMA_MCP', 'Error during client close (subprocess may already be dead)', { error: String(error) });
+      }
     }
 
     getSupervisor().unregisterProcess(CHROMA_SUPERVISOR_ID);
@@ -394,7 +412,10 @@ export class ChromaMcpManager {
           'uvx --with certifi python -c "import certifi; print(certifi.where())"',
           { encoding: 'utf8', stdio: ['pipe', 'pipe', 'pipe'], timeout: 10000 }
         ).trim();
-      } catch {
+      } catch (error) {
+        logger.debug('CHROMA_MCP', 'Failed to resolve certifi path via uvx', {
+          error: error instanceof Error ? error.message : String(error)
+        });
         return undefined;
       }
 
@@ -408,7 +429,10 @@ export class ChromaMcpManager {
           'security find-certificate -a -c "Zscaler" -p /Library/Keychains/System.keychain',
           { encoding: 'utf8', stdio: ['pipe', 'pipe', 'pipe'], timeout: 5000 }
         );
-      } catch {
+      } catch (error) {
+        logger.debug('CHROMA_MCP', 'No Zscaler certificate found in system keychain', {
+          error: error instanceof Error ? error.message : String(error)
+        });
         return undefined;
       }