v0.2.10

v0.2.10 — Change-detection notifications

Adds desktop notifications for three new MR change events detected during background refreshes, on top of the existing branch-detection alert.

- `updated_at` changed — notifies when GitLab reports a newer timestamp than the locally stored one
- Mergeability changed — notifies on any status transition (e.g. `Mergeable → Conflict`, `NeedsRebase → Mergeable`)
- Milestone changed — notifies when the milestone attached to an MR is updated or removed

- Change notifications are suppressed during the initial sync on launch
- A `pending_initial_fetches` counter tracks how many MRs are still awaiting their first API response; toasts are only sent once the counter reaches zero (i.e. from the second refresh cycle onward)
- Prevents spurious toasts caused by in-memory placeholders (`"Loading"`, `Unknown`) being replaced by real values on first fetch

- Added `Draft`, `CiMustPass`, `CiStillRunning`, `NotApproved`, `RequestedChanges` variants
- Full mapping of all known `detailed_merge_status` values returned by GitLab ≥ 15.6
- Legacy `merge_status` fallback preserved for GitLab < 15.6

- `tracing::info!` calls log every detected change (old → new) to the rolling log file at `~/.config/gitlab-tracker/gitlab-tracker.log`