fix(git): the interval fetches one run per folder, and the rest of the review (review)

The scheduler is the part that runs with nobody watching, so it is decided per folder
rather than per session: sessions sharing a folder are the same clone and share one run
that both see, `inFlight`/`lastRunAt` are keyed by the resolved folder, the schedule is
stamped when a folder is picked instead of when its run starts, and a tick is skipped
while the previous one is still going. The click route joins a run already going for the
same folder rather than starting a second fetch in one clone.

The tick keeps ONE bound for the git processes of the whole run and hands it to every
folder, and bounds its folders with a bound of its own: the same semaphore cannot serve
both levels, because a folder holding a slot would then wait for a slot its own fetch
needs. Both bounds are `FETCH_CONCURRENCY`, so the ceiling is unchanged. The bound claim
in CLAUDE.md, the `Limiter` jsdoc and docs/api-reference.md now describes it as it is.

Before anything is fetched the folder is probed with the bounded path probe, so a case on
a mount that stopped answering is skipped and never touched.

The rest of the review: the hooks are named as they really are (`reference-transaction`,
`pre-auto-gc` through the maintenance a fetch triggers, config commands such as
`credential.helper`) and `FETCH_CONFIG_ARGS` turns maintenance and gc off for an
unattended run; the claim that an agent in the same repository is not disturbed is
replaced by the ref-lock collision it actually is; the click route publishes its own run
as `trigger: 'click'`; `autoSaveGitFetch` uses `_apiJson` so a 400 shows the error toast
and applies the returned settings; and the two wording fixes.

Tests: the scheduler pins one run per folder, the two bounds, the probe before anything
runs, and that closing the session holding the override keeps the folder while another
session is still open on it; the route test pins the click publish and the join, asserting
the join before the held run is released — releasing first lets the run finish and clears
the lane, so the joiner would be entitled to its own fetch and the test would pass for the
wrong reason.

src/types/session.ts

@@ -893,14 +893,18 @@ export interface SessionState {
   /** What the keep-warm is doing right now; ephemeral, never restored. */
   keepWarm?: KeepWarmStatus;
   /**
-   * Git fetch on an interval for this case's repositories; absent = follow the app-wide
+   * Git fetch on an interval for this session's repositories; absent = follow the app-wide
    * `gitFetchEnabled` default. Restored on a restart, like `keepWarmEnabled`, because the choice is the
    * user's and outlives the run.
    */
   gitFetchEnabled?: boolean;
-  /** Seconds between this case's runs; absent = follow the app-wide `gitFetchIntervalSeconds` default. */
+  /** Seconds between this session's runs; absent = follow the app-wide `gitFetchIntervalSeconds` default. */
   gitFetchIntervalSeconds?: number;
-  /** What this case's last fetch did; ephemeral, never restored. */
+  /**
+   * What this session's last fetch did. Written to disk with the rest of the record, but the restore copies
+   * only the fields its own config lists and this is not one of them, so it is the panel's truth for the
+   * life of the session, not across a restart.
+   */
   gitFetch?: GitFetchStatus;
   /** Pinned to the top of the session manager list (COD-139) */
   pinned?: boolean;