Cover SVN watcher recovery and lifecycle transitions

[lzl51230]

Scope

Add deterministic watcher-level tests for the recovery and lifecycle branches introduced by #1113. Current tests cover baseline/dedup, callback return retries, and inherited-parent Git precedence.

Coverage

• Edit during callback and staged-observation acknowledgement.
• Missing client and malformed/nonzero status recovery.
• Failed root-Git probe retains Git-first precedence.
• Definitive non-working-copy settlement.
• File-count interval refresh and completion-relative SVN scheduling.
• Replacement/unwatch during active polling and callback.
• Shutdown and missing-root pruning for SVN registrations.

[DeusData]

Tracked as 0.9.2-rc lifecycle coverage for #1113/#1127. Replacement/unwatch during an active callback, failed-client recovery, acknowledgement after success, and shutdown pruning are core correctness paths and should be deterministic before the watcher feature is considered stable. Timing-only sleeps are not sufficient guards for these races.