feat: add Firo network support

[reubenyap]

Summary

This PR adds complete Firo chain integration to the Rosen Bridge UI, following the established UTXO chain pattern used by Doge and Bitcoin.

Note: This PR supersedes #15 and incorporates all of its changes along with fixes for the review feedback raised there.

Commits

The PR is structured as two commits for easy review:

1. feat: add Firo network support — The full Firo integration (equivalent to the changes in add firo support #15)
2. fix: address review feedback on Firo integration — Fixes for the issues identified in the add firo support #15 review

Changes

Firo Integration (commit 1)

• networks/firo/: Network package with client class, constants, types, UTXO selection, transaction generation, and BlockCypher API utilities
• wallets/firo-wallet/: Wallet package with browser extension integration (connect, sign, broadcast)
• apps/rosen/: App wiring with server actions, lock address config, and wallet registration
• packages/constants: Add Firo to NETWORKS (index 7, native token: firo)
• packages/icons: Add Firo network SVG icon
• packages/utils: Add Firo explorer URLs (address, token, tx)
• apps/rosen-service: Gracefully skip unconfigured chains in commitment extractor registration
• apps/rosen/.env.example: Add FIRO_BLOCKCYPHER_API variable

Review Fixes (commit 2)

Addresses the feedback from #15:

• build.sh: Add networks/firo and wallets/firo-wallet workspaces to the build script (per BEK documentation requirement, as noted by @abdolian)
• firo.svg: Remove XML declaration and unnecessary attributes; keep only viewBox and xmlns consistent with other network SVGs (as noted by @abdolian)
• getMaxTransfer.ts: Fix typo opRetrunDataLength → opReturnDataLength
• utils.ts: Fix incorrect JSDoc @param references

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