Simplify compaction: remove proactive abort, use Agent.continue() for retry

- Add agentLoopContinue() to pi-ai for resuming from existing context
- Add Agent.continue() method and transport.continue() interface
- Simplify AgentSession compaction to two cases: overflow (auto-retry) and threshold (no retry)
- Remove proactive mid-turn compaction abort
- Merge turn prefix summary into main summary
- Add isCompacting property to AgentSession and RPC state
- Block input during compaction in interactive mode
- Show compaction count on session resume
- Rename RPC.md to rpc.md for consistency

Related to #128

packages/agent/vitest.config.ts

@@ -4,6 +4,6 @@ export default defineConfig({
 	test: {
 		globals: true,
 		environment: "node",
-		testTimeout: 10000, // 10 seconds
+		testTimeout: 30000, // 30 seconds for API calls
 	},
 });