fix: speak to older mints again, in forms every generation reads (0.25.1)

[TheCryptoDonkey]

0.25.0 moved to @lnurlcash/kit 0.20.2, which speaks only LUD-25's renamed wire forms (?p=<cp1>, p1/p2, a cp1 quote comment). Mints from before the renames (the reference lnurl-mint, moneyer before 0.12) read none of those, so 0.25.0 could not look up, receive, check, rotate, split, merge, send, melt or mint a bearer note at one.

What changes

A bearer note goes on the wire in forms every mint generation reads. Nothing waits for a refusal and retries in another shape; the rule for when that would be allowed is written down in src/lnurlcash-network.ts.

• Lookup (receive, check, probe, reconcile, the mint-claim poll): the note's own ?k1=, which every mint answers (a current one checks the spend in full).
• Rotate / split / merge: each output's 64-hex h under both p1 and h (p2 and h2). An old mint reads h and ignores p1; moneyer 0.12+ reads either and requires them to agree. The merge batcher counts both names.
• Mint quote: the hash as both comment and h. A mint that binds only by h (advertising mintToHash, no commentAllowed) can be added again, and must confirm mintToHash on the quote or the invoice is dropped unshown.
• Melt: unchanged (k1, pr).
• Restore: unchanged. An old mint has no secret-free lookup, so it still needs allowSecretDisclosure, as designed.
• Certificates: an older mint certifies only over a bearer note's h, as hex or fixed-HRP cs1 (sig/sig2). 0.25.0 refused every certified note from one once its key was pinned, and could never take one offline. For a 64-hex k1 these now verify under the rule they were made under, rotates keep them, and they are sent as sig= beside amount=. On a ck1/cw1 they still verify nowhere. This reverses that part of 0.25.0's changelog.
• Key-path and script-path notes (ck1, cw1) exist only at current mints and stay on the kit's forms.

Tests

test/old-mints.test.ts grades every bearer-note operation against moneyer 0.17, moneyer 0.3.1 (moneyer-legacy, an npm alias) and lnurlcash-conformance 0.13.1's mock mint (lnurlcash-conformance-0-13). All three run in process, with no real mints and no sats. On main, all 23 old-mint cases fail (and the 6 updated unit and integration tests too) (lookups NoteUnknownError, mutations missing h, a 0.3.1 mint refused by addMint). On this branch all of them pass. The mock's invoices don't decode as BOLT-11, so the full mint flow there is graded at the wire only.

npm run check is green.