fix: use bio_selectAccount for biobridge external account

[Gaubee]

Summary

• route biobridge external account selection through bio_selectAccount for all external chains
• remove direct window.ethereum / window.tronLink account sourcing from biobridge connect step
• add regression test to ensure ETH flow uses bio_selectAccount and not eth_requestAccounts

Why

User reports showed BSC forge flow could pick a non-expected address. This change enforces KeyApp account selection as the single source of truth for forge sender address in miniapp runtime.

Validation

• Added unit regression test in miniapps/biobridge/src/App.test.tsx
• Local test run was blocked by missing Storybook/Vitest workspace deps in current environment; CI to verify fully.