feat(app): flag transactions above the newest checkpoint as not anchored

Blocks mined after the newest hardcoded checkpoint cannot be chained to it,
so only the Merkle proof against the server's header backs them. The
history list and the transaction detail now show a 'not anchored' label
for those transactions. Informational only: spending is not blocked.
See ADR 0041.

docs/adr/README.md

@@ -44,6 +44,7 @@ One ADR per feature or significant design decision. Format: `template.md`. Workf
 | 0038 | [CLI password sources and explicit plaintext storage](0038-cli-password-sources-and-explicit-plaintext.md) | Distribution | Accepted |
 | 0039 | [Server fee estimates, relay floor and a high-fee warning](0039-server-fee-estimates-and-relay-floor.md) | Wallet | Accepted |
 | 0040 | [Anchor headers up to a checkpoint above them](0040-anchor-headers-up-to-a-checkpoint.md) | SPV | Accepted |
+| 0041 | [Flag transactions above the newest checkpoint as not anchored](0041-flag-transactions-above-the-newest-checkpoint.md) | SPV | Accepted |
 
 ADRs `0002` onwards were written retroactively on 2026-11-03 from the code, comments and changelog. 
 If one misstates the original reasoning, fix it in a pull request.