fix: decode uppercase Bitcoin addresses

[jvsena42]

Fixes #707

This PR moves all decode() calls to CoreService and adds a workaround for uppercase Bitcoin address decoding.

Description

• Adds decode() method to CoreService that wraps the bitkitcore binding with a lowercase workaround
• Migrates all 8 direct decode() calls from AppViewModel, WalletRepo, LightningRepo, and AutoReadClipboardHandler to use the centralized service method
• Adds canDecodeClipboard() method to AppViewModel for clipboard detection
• Includes TODO comment to remove the workaround when bitkit-core#66 is fixed

Preview

onchain.webm

lightning.webm

clipboard.webm

QA Notes

1. Scan an uppercase Bitcoin address

   • Use QR scanner or paste bitcoin:BCRT1QEAN25UPQWQA4NC5EH0M23U6UHLKWR4R5DGMN5C
   • Verify it decodes correctly and navigates to send flow

2. Scan a lowercase Bitcoin address

   • Verify normal addresses still work as expected

3. Test clipboard auto-read

   • Copy an uppercase Bitcoin address to clipboard
   • Open app, verify clipboard detection prompt appears

4. Test Lightning invoice decoding

   • Scan a Lightning invoice
   • Verify it decodes and shows payment details

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

[ovitrif]

@jvsena42 did you test manually?!

If yes, please add a marker to the tests in the PR description, like:
🟢 or ✅ 🙏🏻

Allows one to utAck & merge with peace of mind

[ovitrif]

utAck.

Pending confirmation if safe to merge (if you tested it locally)

e2e succeeded anyways so it's definitely not a risk to auto-merge.

[jvsena42]

@jvsena42 did you test manually?!

If yes, please add a marker to the tests in the PR description, like: 🟢 or ✅ 🙏🏻

Allows one to utAck & merge with peace of mind

Yes, added the video on description