Tech Debt Scanner

Scan the codebase for common Elixir/Phoenix tech debt patterns.

Check for

1. Dead code: Unused functions, modules, aliases
   • mix xref unreachable
   • Grep for # TODO, # FIXME, # HACK
2. Duplicated code: Similar function bodies across modules
3. Missing typespecs: Public functions without @spec
4. Large modules: Files > 300 lines
5. Missing tests: Modules in lib/ without corresponding test/ files
6. Deprecated patterns: Old Phoenix/Ecto patterns
7. Credo issues: mix credo --strict --format json

Output format

Priority-sorted list with file:line references and suggested fixes.