Git browser: M1 foundation

- Add `file_system/git/` module: `discover_repo` via `gix::discover` (follows gitlinks), `repo_info` (branch, ahead/behind, dirty), `list_status` (porcelain v2 shell-out), notify-rs watcher, and friendly errors
- Wire IPC commands `get_git_repo_info`, `subscribe_git_state`, `unsubscribe_git_state`, `get_git_status_for_paths` with `blocking_with_timeout` and `git-state-changed` event
- Schema additions inert until M2/M3: `FileEntry.redirectToPath`, four `git:*` icon IDs, `--color-git-portal` CSS token
- Frontend `file-explorer/git/` module: `RepoChip.svelte` (six visual states) + `git-store.svelte.ts` (refcounted per-repo subscriptions) + `status-column.ts` helpers
- `FilePane.svelte` drives the chip via `lookupRepoInfo` + `subscribeToRepo`; refresh on `git-state-changed`, no polling
- `FullList.svelte` adds an optional Git column right after Name, gated by `fileExplorer.git.showStatusColumn` and only rendered inside a worktree; refreshes from `fetchStatusMap` on `git-state-changed`
- Settings: `fileExplorer.git.showRepoChip`, `showStatusColumn`, `showVirtualGitPortal`
- Bench: discover + repo_info p95 ~66 ms, list_status p95 ~75 ms on a 50k-file synth fixture (under the 100 ms hard cap)
- Decision documented: shell out to `git status --porcelain=v2 -z` because gix's status iter missed staged adds in our fixtures
- Docs: new CLAUDE.md in `file_system/git/` and `file-explorer/git/`; updates to `file-explorer/CLAUDE.md`, `views/CLAUDE.md`, `volume/CLAUDE.md`, `docs/architecture.md`; CHANGELOG entry under [Unreleased]

Author: vdavid

CHANGELOG.md

@@ -5,6 +5,18 @@ All notable changes to Cmdr will be documented in this file.
 The format is based on [keep a changelog](https://keepachangelog.com/en/1.1.0/), and we use
 [Semantic Versioning 2.0.0](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Added
+
+- **Git repo chip in the breadcrumb.** Open a folder inside a git clone and the breadcrumb shows a chip with the current
+  branch, ahead/behind counts vs the upstream, and a "dirty" indicator when the worktree has uncommitted changes.
+  Detached HEAD shows the short SHA; freshly-initialized repos show "no commits yet". Updates live as you commit, fetch,
+  or branch from the terminal — no polling, no refresh button. Toggle via **Settings > General > Git > Show repo chip**.
+  Foundation for the upcoming `.git` virtual portal (next milestone).
+- **Optional Git status column in Full mode.** Adds a single-glyph column (`M`, `A`, `D`, `?`, `!`) showing each file's
+  git status. Hidden by default; enable in **Settings > General > Git > Show git status column**.
+
 ## [0.14.0] - 2026-04-26
 
 ### Added