test: cover verifier batchApprove/batchReject duplicate & all-unknown id edge cases

[Dennis-Ritchie1]

test: cover verifier batchApprove/batchReject duplicate & all-unknown id edge cases

Closes #335

Summary

src/Zustand/Store.ts's batchApprove/batchReject are implemented by calling
the single-task mutators per id via get(). The store already had tests for the
core batch path (transitions, mixed unknown ids, notes propagation, empty list),
but the duplicate id and all-unknown id edge cases called out in the issue
were not directly verified. This PR adds that coverage.

Changes

• Added a test asserting a duplicated id is processed only once — no throw, no
  duplicate entry in history, and the task lands as approved.
• Added a test asserting an all-unknown id list is a no-op for both
  batchApprove and batchReject (pending queue untouched, history stays empty).

Both tests follow the existing pattern: the store is reset between tests via
useVerifierStore.setState(...) in beforeEach.

Testing

• npx vitest run src/Zustand/__tests__/Store.test.ts → 8 tests passing.
• Store.ts: 100% branch coverage; the verifier batch/single mutators are fully
  covered (the only uncovered lines belong to the unrelated notification store).
• No changes to production code — tests only, so no regression risk to batch validation.

Notes for reviewer

The core batch tests already exist on main (from an earlier commit), so this is a
small, focused extension covering the two remaining edge cases from the issue.
The diff is limited to src/Zustand/__tests__/Store.test.ts.