docs: add mkdocs, update links, add architecture documentation

docs/content/stories/phase6/6.1.2-create-custom-spans.md

@@ -0,0 +1,40 @@
+# Task 6.1.2: Create custom spans:
+
+## Metadata
+- **Task ID**: 6.1.2
+- **Title**: Create custom spans:
+- **Phase**: 6 - Observability & Production Readiness
+- **Section**: 6.1
+- **Status**: Pending
+- **Priority**: High
+- **Estimated Time**: TBD
+- **Dependencies**: TBD
+
+## Description
+Create custom spans:
+
+## Requirements
+- Create custom spans:
+
+## Implementation Steps
+1. TODO: Add implementation steps
+2. TODO: Add implementation steps
+3. TODO: Add implementation steps
+
+## Acceptance Criteria
+- [ ] Task 6.1.2 is completed
+- [ ] All requirements are met
+- [ ] Code compiles and tests pass
+
+## Related ADRs
+- See relevant ADRs in `docs/adr/`
+
+## Implementation Notes
+- TODO: Add implementation notes
+
+## Testing
+```bash
+# TODO: Add test commands
+go test ./...
+```
+