a213677cf0
Adds _render_ast_inspector_file_content_result(app, f_path) -> Result[str | None] helper that wraps the mcp_client.read_file try/except in render_ast_inspector_modal. On success, returns the file content string. On failure, returns Result(data=None, errors=[ErrorInfo]). The legacy wrapper handles the side effects (sets app._cached_ast_file_lines + app.text_viewer_content) and drains errors to app._last_request_errors (per FR-BC-3 modal pattern; data plane attribute). Audit: BROAD_CATCH count 15 -> 14, COMPLIANT count 22 -> 23. Migration target count drops by 1. All 3 Phase 4 sites migrated. Tests: 2/2 pass.