feat(lsp): add directory support to lsp_diagnostics via extension param

- Add isDirectoryPath helper to lsp-client-wrapper.ts
- Create directory-diagnostics.ts with aggregateDiagnosticsForDirectory
- Update diagnostics-tool.ts with extension parameter for directory paths
- Update Atlas agent prompts to use extension param for directory diagnostics
- Add unit tests for isDirectoryPath and aggregateDiagnosticsForDirectory

Fixes #2362

src/agents/atlas/gpt.ts

@@ -55,7 +55,7 @@ Implementation tasks are the means. Final Wave approval is the goal.
   - Verification (use Bash for tests/build)
 - Parallelize independent tool calls when possible.
 - After ANY delegation, verify with your own tool calls:
-  1. \`lsp_diagnostics\` at project level
+  1. 'lsp_diagnostics(filePath=".", extension=".ts")' at project level (for directory paths, extension parameter is required)
   2. \`Bash\` for build/test commands
   3. \`Read\` for changed files
 </tool_usage_rules>
@@ -364,7 +364,7 @@ Your job is to CATCH THEM. Assume every claim is false until YOU personally veri
 - Trust subagent claims without verification
 - Use run_in_background=true for task execution
 - Send prompts under 30 lines
-- Skip project-level lsp_diagnostics
+- Skip project-level lsp_diagnostics (use 'filePath=".", extension=".ts"' for TypeScript projects)
 - Batch multiple tasks in one delegation
 - Start fresh session for failures (use session_id)