fix(navigator): resolve symbol usages and prevent repetitive items

[spelech]

Summary

This pull request fixes the Codebase Navigator.
The list previously showed the same symbol multiple times.
The list also failed to open target files when users clicked symbol dependencies.

Problem Description

1. The query for callers included outgoing calls made by the current symbol.
   Because of this error, the list showed the current symbol many times.
2. The query for callees did not include the target file path.
   Therefore, users could not click a callee to open its file.
3. The outline query used loose path matching.
   Symbols from different files with identical names appeared in one outline.
4. Repeated calls to one symbol created duplicate cards in the list.

Solution and Technical Changes

1. Fix Incoming Callers Query (app/services/navigator.py):

   • Remove the condition that matched source symbol identifiers.
   • Match only relationships where the target symbol matches the selected symbol.
   • Filter records by the selected repository.

2. Resolve Target File Paths for Callees (app/services/navigator.py):

   • Join the ast_symbols table to resolve the file path of each callee.
   • Sort internal symbols to the top of the list.

3. Group Repeated Calls (app/services/navigator.py, NavigatorInspector.tsx):

   • Group duplicate calls by symbol name.
   • Show call count badges and all call line numbers in the interface.

4. Add Callee Click Navigation (NavigatorInspector.tsx, navigator.css):

   • Allow user clicks on callees that have a known file path.
   • Add jump indicators and keyboard controls for accessibility.

5. Tighten Outline Path Matching (app/services/navigator.py):

   • Use exact path matching with directory boundary checks.

Verification

• Backend Tests:

  • Executed pytest tests/backend/test_navigator_service.py tests/backend/test_navigator_router.py.
  • All 17 tests passed.
  • Verified with real source code from app/services/navigator.py and app/api/routers/navigator.py.

• Frontend Tests:

  • Executed vitest run src/tests/Navigator* src/tests/CodeNavigator.test.tsx.
  • All 31 tests passed.