migrate mosaic home to xdg config path

guides/backend.md

@@ -1,7 +1,7 @@
 # Backend Development Guide
 
 ## Before Starting
-1. Check assigned issue: `~/.mosaic/rails/git/issue-list.sh -a @me`
+1. Check assigned issue: `~/.config/mosaic/rails/git/issue-list.sh -a @me`
 2. Create scratchpad: `docs/scratchpads/{issue-number}-{short-name}.md`
 3. Review API contracts and database schema
 
@@ -47,7 +47,7 @@
 - Use project's established auth pattern
 - Validate tokens on every request
 - Check permissions before operations
-- See `~/.mosaic/guides/authentication.md` for details
+- See `~/.config/mosaic/guides/authentication.md` for details
 
 ## Testing Requirements (TDD)
 1. Write tests BEFORE implementation
@@ -73,7 +73,7 @@ class TestResourceEndpoint:
 
 ## Code Style
 - Follow Google Style Guide for your language
-- **TypeScript: Follow `~/.mosaic/guides/typescript.md` — MANDATORY**
+- **TypeScript: Follow `~/.config/mosaic/guides/typescript.md` — MANDATORY**
 - Use linter/formatter from project configuration
 - Keep functions focused and small
 - Document complex business logic