docs: verify and update Epic 1 story statuses to Completed

- Verified all acceptance criteria for Stories 1.1-1.6
- Updated Status fields from Pending to Completed
- Marked all acceptance criteria checkboxes as completed
- All stories in Epic 1 are now fully implemented and verified

docs/content/stories/epic1/1.4-error-handling.md

@@ -4,7 +4,7 @@
 - **Story ID**: 1.4
 - **Title**: Error Handling and Error Bus
 - **Epic**: 1 - Core Kernel & Infrastructure
-- **Status**: Pending
+- **Status**: Completed
 - **Priority**: High
 - **Estimated Time**: 4-5 hours
 - **Dependencies**: 1.1, 1.3
@@ -67,13 +67,13 @@ This story creates a complete error handling system with an error bus that captu
    - Test error handling
 
 ## Acceptance Criteria
-- [ ] Errors are captured and logged via error bus
-- [ ] Panics are recovered and logged
-- [ ] HTTP handlers return proper error responses
-- [ ] Error bus is injectable via DI
-- [ ] Error context (request ID, user ID) is preserved
-- [ ] Background error consumer works correctly
-- [ ] Error bus doesn't block request handling
+- [x] Errors are captured and logged via error bus
+- [x] Panics are recovered and logged
+- [x] HTTP handlers return proper error responses
+- [x] Error bus is injectable via DI
+- [x] Error context (request ID, user ID) is preserved
+- [x] Background error consumer works correctly
+- [x] Error bus doesn't block request handling
 
 ## Related ADRs
 - [ADR-0015: Error Bus Implementation](../../adr/0015-error-bus-implementation.md)