fix(bridge): allow idle permission mode changes

[Edwiv]

Summary

• Let permission mode changes update bridge state even when the Claude SDK query iterator is idle.
• Apply the selected mode to the next turn instead of throwing from an idle process.
• Add SDK process coverage for idle permission mode changes.

Why

Users can change permission mode between turns. That should be recorded immediately and used by the next query, not rejected because no query is currently active.

Tests

• npm ci --ignore-scripts
• npm run test --workspace=packages/bridge -- src/sdk-process.test.ts
• npx tsc --noEmit -p packages/bridge/tsconfig.json