chore(tools): Workspace path validation and dir move support

[JeanMertz]

All filesystem tools previously validated user-supplied paths through ad-hoc inline checks (is_absolute, trim_start_matches, etc.) with no protection against symlink escape attacks. This commit replaces those scattered checks with a shared check_workspace_path pipeline in fs/utils.rs and two public entry points:

• resolve_workspace_path — canonicalizes through symlinks on existing ancestors, guaranteeing the result lies inside the workspace root. Used by write tools (create_file, delete_file, modify_file, move_file, read_file).
• clean_workspace_path — lexically normalizes without following symlinks, while still verifying the canonical ancestor stays in-root. Used by read/search tools (grep_files, list_files) where the returned path should match the user's input shape.

The validator rejects absolute paths, ..-escape attempts that survive normalization, symlinks whose canonical target falls outside the root, path components exceeding 100 bytes, and paths with more than 20 components.

fs_move_file was also expanded to handle directories in addition to files: directories are moved atomically with fs::rename, require the target to not already exist, and get a broader dirty check via count_dirty_paths_impl (any non-empty git status --porcelain line counts). A same-path guard prevents no-op moves, and the success message now distinguishes between file and directory moves. The tool description in .jp/mcp/tools/fs/move_file.toml is updated to reflect the new capability.