fix(desktop): retry store writes on Windows EPERM - #51474

Issue for this PR

Closes #51470

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

store-set, store-delete and store-clear called electron-store directly, so when the final rename hit a transient Windows sharing violation (EPERM/EBUSY/EACCES) the error was thrown straight back into the renderer and the write was silently lost — the store kept its old contents and the change disappeared on the next reload. Log line in #51470.

The three handlers now go through mutateStore (store-write.ts):

• It retries the mutation up to 3 times with a short backoff. conf/atomically already retry the rename itself for 1s, but that is a hot sync loop that blocks the main process; the extra attempts are awaited with a timer in between, so the event loop gets a chance to run between them.
• If the write still fails, it applies the same mutation to the data read from disk and writes the file in place with writeFileSync. That is not atomic, but a tiny JSON file that survives a crash mid-write is the better trade against dropping the user's change and keeping the stale file. If even that fails, it logs and resolves instead of rejecting into the renderer.
• Mutations of the same store file are serialized per name, so two concurrent IPC writes cannot race each other's rename, and the fire-and-forget removeStoreFileIfEmpty after delete/clear now runs through the same queue instead of reading/deleting the file while a write is renaming onto it.

Errors that are not transient still propagate to the renderer exactly as before.

How did you verify your code works?

• bun test in packages/desktop: added store-write.test.ts with 5 tests (retry until it lands, in-place fallback, non-transient errors rejected, per-file serialization, unrelated stores not blocked) — all pass; the two pre-existing failures in that package (draft-store, wsl/servers) fail identically on a clean checkout here because of this machine's environment (node:sqlite missing, Electron binary not installed).
• bun run typecheck in packages/desktop passes.
• bun run lint: no findings on the changed files.

Screenshots / recordings

Not a UI change.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR