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/worker/SDKAgent.ts

@@ -480,7 +480,11 @@ export class SDKAgent {
       if (claudePath) return claudePath;
     } catch (error) {
       // [ANTI-PATTERN IGNORED]: Fallback behavior - which/where failed, continue to throw clear error
-      logger.debug('SDK', 'Claude executable auto-detection failed', {}, error as Error);
+      if (error instanceof Error) {
+        logger.debug('SDK', 'Claude executable auto-detection failed', {}, error);
+      } else {
+        logger.debug('SDK', 'Claude executable auto-detection failed with non-Error', {}, new Error(String(error)));
+      }
     }
 
     throw new Error('Claude executable not found. Please either:\n1. Add "claude" to your system PATH, or\n2. Set CLAUDE_CODE_PATH in ~/.claude-mem/settings.json');