bug: uppercase bech32 addresses rejected by detect_address_type, breaking BIP-137 verify

[jaso0n0818]

Summary

detect_address_type() uses case-sensitive startswith('bc1q') / startswith('bc1p') checks. Valid BIP-173 bech32 addresses may be encoded in all-uppercase; these are classified as unknown, so sign_from_proof() / verify_from_proof() fail before any cryptographic verification.

Affected code

allways/chain_providers/bitcoin.py — detect_address_type() (lines ~26-45), used by reserve/confirm proof flows.

Reproduction

from allways.chain_providers.bitcoin import detect_address_type
detect_address_type('bc1qw508d6qejxtdg4y5r3zarvvary0c5xw7kv8f3t4')  # -> 'unknown'

Lowercase equivalent correctly returns p2wpkh.

Impact

Users or wallets emitting uppercase bech32 cannot complete BTC-sourced swap reserve/confirm proofs via external BIP-137 signing.

Suggested fix

Normalize with address.lower() before prefix checks (reject mixed-case per BIP-173).

Environment

mainnet P2WPKH/P2TR uppercase bech32 strings; observed in verify_from_proof path.

[jaso0n0818]

Filed for issue-discovery track. Reproducible with uppercase bech32 mainnet address; detect_address_type returns unknown.

[jaso0n0818]

Opened PR #475 with fix + tests (46/46 test_bitcoin_signing.py pass). Ready for review.