Generate valid wallet user scan ids in tests

[a-shannon]

Wallet test generators choose user scan IDs strictly above PaymentsScanId while retaining payment-only, user-only and mixed scan cases. This avoids generating reserved IDs that cannot represent registered user scans.

Head ccc421cb1f8cab249c0a37f0bf918d59e76bc354 targets master and retains the one-file wallet review increment, including master's generator-managed selection and corrected OffChainRegistrySpec precondition. The wallet generator and its assertions are byte-identical to the reviewed source.

The new eleven-file prerequisite increment adds settled-seed/isolation D, owned by #2535, plus exact production corrections G, owned by #2511, and X, owned by #2549. The cumulative PR therefore includes four shared production paths alongside its original test-only correction.

G anchors full V2 summaries at genesis, keys cached summaries by selected tip and mode, and schedules missing sections from a retained common ancestor. X wakes retained block sections after their headers arrive. Review R, owned by #2535, before G; merge the owning #2511/#2549 corrections before this consumer. Exact common commits preserve single ownership without requiring the complete #2535 branch as a parent.

Existing H, U and T remain unchanged. U compares the four selected headers under the original targets and fifteen-minute deadline. T collects typed observations only after timeout, within a separate 2.5-second budget, and always preserves the original failure. D preserves DeepRollBack's convergence assertions and deadlines while establishing a settled, non-mining seed and actual isolation.

At 9b710e309, native IT passed 49/50; DeepRollBack alone timed out at minimum 251. The earlier cc08 CI passed every wallet/core/node job and 44/45 IT cases, with a real selected-header disagreement across the four nodes. These are distinct historical observations. The shared G/X defects are independently established; exclusive attribution of either timeout is not claimed.

The actual final composition passed normal compilation and 49/49 focused synchronizer/history/cache tests, including both UTXO and Digest wake-up cases. Its preceding D composition passed normal IT compilation and H/D 33/33; unchanged H/T 37/37 and wallet 39/39 results remain input-qualified prior evidence. Independent source review found no blockers. The local gates did not run Docker or establish full CI success. New-head native CI remains pending in #2533.