refactor: replace happy_path_error__with_fallback with logger.happyPathError (#313)

- Removed all instances of happy_path_error__with_fallback from various hooks, services, and utilities.
- Introduced logger.happyPathError for consistent logging of unexpected nulls and fallback values.
- Updated the logger utility to include a new happyPathError method with enhanced context and stack trace.
- Deprecated silent-debug utility as all logging functionality has been migrated to the logger.

src/utils/tag-stripping.ts

@@ -11,7 +11,7 @@
  * This keeps the worker service simple and follows one-way data stream.
  */
 
-import { happy_path_error__with_fallback } from './silent-debug.js';
+import { logger } from './logger.js';
 
 /**
  * Maximum number of tags allowed in a single content block
@@ -41,14 +41,14 @@ function countTags(content: string): number {
  */
 export function stripMemoryTagsFromJson(content: string): string {
   if (typeof content !== 'string') {
-    happy_path_error__with_fallback('[tag-stripping] received non-string for JSON context:', { type: typeof content });
+    logger.happyPathError('SYSTEM', 'received non-string for JSON context', undefined, { type: typeof content }, '{}');
     return '{}';  // Safe default for JSON context
   }
 
   // ReDoS protection: limit tag count before regex processing
   const tagCount = countTags(content);
   if (tagCount > MAX_TAG_COUNT) {
-    happy_path_error__with_fallback('[tag-stripping] tag count exceeds limit, truncating:', {
+    logger.warn('SYSTEM', 'tag count exceeds limit', undefined, {
       tagCount,
       maxAllowed: MAX_TAG_COUNT,
       contentLength: content.length
@@ -73,14 +73,14 @@ export function stripMemoryTagsFromJson(content: string): string {
  */
 export function stripMemoryTagsFromPrompt(content: string): string {
   if (typeof content !== 'string') {
-    happy_path_error__with_fallback('[tag-stripping] received non-string for prompt context:', { type: typeof content });
+    logger.happyPathError('SYSTEM', 'received non-string for prompt context', undefined, { type: typeof content }, '');
     return '';  // Safe default for prompt content
   }
 
   // ReDoS protection: limit tag count before regex processing
   const tagCount = countTags(content);
   if (tagCount > MAX_TAG_COUNT) {
-    happy_path_error__with_fallback('[tag-stripping] tag count exceeds limit, truncating:', {
+    logger.warn('SYSTEM', 'tag count exceeds limit', undefined, {
       tagCount,
       maxAllowed: MAX_TAG_COUNT,
       contentLength: content.length