Update Claude ACP runtime to 0.35.0

[jsgrrchg]

Summary

• Update the vendored @agentclientprotocol/claude-agent-acp runtime to 0.35.0 and regenerate dist/.
• Bridge ACP SessionUpdate::Plan into NeverWrite's existing ai://plan-updated event.
• Keep plan streaming separate from tool activity, permission diffs, and change-control state.

Why

Claude Agent SDK 0.3.143 moves headless/SDK planning from TodoWrite toward TaskCreate / TaskUpdate / TaskList / TaskGet. Upstream Claude ACP now accumulates those task updates and emits ACP plan session updates. NeverWrite already had frontend support for ai://plan-updated, but the native ACP bridge was ignoring SessionUpdate::Plan, so live plan updates could be dropped after the runtime upgrade.

Validation

• npm install in vendor/Claude-agent-acp-upstream
• npm run build in vendor/Claude-agent-acp-upstream
• npm run test:run in vendor/Claude-agent-acp-upstream
• cargo fmt --package neverwrite-native-backend
• cargo test -p neverwrite-native-backend session_plan_update_emits_plan_event_without_tool_activity
• cargo test -p neverwrite-native-backend ai::tests
• git diff --check

Notes

Also verified locally that the hot dev app was running the staged Claude ACP 0.35.0 runtime from apps/desktop/out/native-backend/embedded/claude-agent-acp.