qr: Add codex32 and wallet-record QR codes

Track all QR work here so it ships together in one minor release.

Background: BlockstreamResearch/codex32#66 (CodexQR) and codex32#56.

Standard QR: the full codex32 string.
Compact QR: the header and payload without the codex32 checksum. A 128-bit share needs 20 bytes, which is 25×25 at ECC Q. A 21×21 code at ECC L holds 17 bytes, so the header must be partly dropped or written beside it.
Show a share's QR on import and after recovery.
Scanning stays optional. Keyboard recovery must not require trusting a camera.
A tiny QR of the wallet record's exact-value fields (fingerprint, descriptor checksum) on the printed record.
Open from gui: Refresh empty wallets automatically #66: a SLIP39-style digest share for detecting wrong share sets.

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