feat(agentos): enable source-loaded Apps

[siwei-yuan]

Summary

• add the minimal raw View SDK and source App runtime while preserving App = Data + Actions + View
• migrate Exa and Robinhood to source-loaded Actions, SQLite projections, and fixed Views
• add retained View reconciliation so source Apps reuse native nodes and emit only changed props/text
• add Settings-only CPU/PSRAM telemetry and center the shared App back control

Scope

This PR contains six focused commits. It does not add Pi Agent candidate iteration or App self-modification.

Validation

• cargo test --workspace
• bun test apps/pi-agent/text.test.ts
• POCKETJS_ROOT=/Users/ysw/Desktop/pocketjs-source-loaded-audit-e12cf12 cargo xtask build pi-agent
• ESP32-P4 release firmware build, flash, and boot validation
• physical source-App install and Exa/Robinhood interaction exercised on the board
• instrumented Robinhood 1D to 1W update: 539 native mutations before, 6 after