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/cli/stdin-reader.ts

@@ -7,6 +7,8 @@
 // to parse after each chunk. Once we have valid JSON, we resolve immediately
 // without waiting for EOF. This is the proper fix, not a timeout workaround.
 
+import { logger } from '../utils/logger.js';
+
 /**
  * Check if stdin is available and readable.
  *
@@ -29,9 +31,10 @@ function isStdinAvailable(): boolean {
     // eslint-disable-next-line @typescript-eslint/no-unused-expressions
     stdin.readable;
     return true;
-  } catch {
+  } catch (error) {
     // Bun crashed trying to access stdin (EINVAL from fstat)
     // This is expected when Claude Code doesn't provide valid stdin
+    logger.debug('HOOK', 'stdin not available (expected for some runtimes)', { error: error instanceof Error ? error.message : String(error) });
     return false;
   }
 }
@@ -49,8 +52,9 @@ function tryParseJson(input: string): { success: true; value: unknown } | { succ
   try {
     const value = JSON.parse(trimmed);
     return { success: true, value };
-  } catch {
-    // JSON is incomplete or invalid
+  } catch (error) {
+    // JSON is incomplete or invalid — expected during incremental parsing
+    logger.debug('HOOK', 'JSON parse attempt incomplete', { error: error instanceof Error ? error.message : String(error) });
     return { success: false };
   }
 }
@@ -128,47 +132,52 @@ export async function readJsonFromStdin(): Promise<unknown> {
       }
     }, SAFETY_TIMEOUT_MS);
 
+    const onData = (chunk: Buffer | string) => {
+      input += chunk;
+
+      // Clear any pending parse delay
+      if (parseDelayId) {
+        clearTimeout(parseDelayId);
+        parseDelayId = null;
+      }
+
+      // Try to parse immediately - if JSON is complete, resolve now
+      if (tryResolveWithJson()) {
+        return;
+      }
+
+      // If immediate parse failed, set a short delay and try again
+      // This handles multi-chunk delivery where the last chunk completes the JSON
+      parseDelayId = setTimeout(() => {
+        tryResolveWithJson();
+      }, PARSE_DELAY_MS);
+    };
+
+    const onEnd = () => {
+      // stdin closed - parse whatever we have
+      if (!resolved) {
+        if (!tryResolveWithJson()) {
+          // Empty or invalid - resolve with undefined
+          resolveWith(input.trim() ? undefined : undefined);
+        }
+      }
+    };
+
+    const onError = () => {
+      if (!resolved) {
+        // Don't reject on stdin errors - just return undefined
+        // This is more graceful for hook execution
+        resolveWith(undefined);
+      }
+    };
+
     try {
-      process.stdin.on('data', (chunk) => {
-        input += chunk;
-
-        // Clear any pending parse delay
-        if (parseDelayId) {
-          clearTimeout(parseDelayId);
-          parseDelayId = null;
-        }
-
-        // Try to parse immediately - if JSON is complete, resolve now
-        if (tryResolveWithJson()) {
-          return;
-        }
-
-        // If immediate parse failed, set a short delay and try again
-        // This handles multi-chunk delivery where the last chunk completes the JSON
-        parseDelayId = setTimeout(() => {
-          tryResolveWithJson();
-        }, PARSE_DELAY_MS);
-      });
-
-      process.stdin.on('end', () => {
-        // stdin closed - parse whatever we have
-        if (!resolved) {
-          if (!tryResolveWithJson()) {
-            // Empty or invalid - resolve with undefined
-            resolveWith(input.trim() ? undefined : undefined);
-          }
-        }
-      });
-
-      process.stdin.on('error', () => {
-        if (!resolved) {
-          // Don't reject on stdin errors - just return undefined
-          // This is more graceful for hook execution
-          resolveWith(undefined);
-        }
-      });
-    } catch {
+      process.stdin.on('data', onData);
+      process.stdin.on('end', onEnd);
+      process.stdin.on('error', onError);
+    } catch (error) {
       // If attaching listeners fails (Bun stdin issue), resolve with undefined
+      logger.debug('HOOK', 'Failed to attach stdin listeners', { error: error instanceof Error ? error.message : String(error) });
       resolved = true;
       clearTimeout(safetyTimeoutId);
       cleanup();