feat(aircoding): AirCoding V2 baseline — deterministic multi-agent architecture

Forked from OpenCode v1.17.4 with multi-agent system:
- 5 agents: aircoding, scheduler, worker, architect, reviewer
- Deterministic DAG scheduling engine (coordinator_tick)
- Tool whitelists as hard enforcement
- AirCoding validation plugin
- System prompt injection for routing
- V1 requirements: C4 docs, ADR, AGENTS.md, debug-log.md
- Design documents in docs/

packages/opencode/src/cli/cmd/debug/startup.ts

@@ -0,0 +1,11 @@
+import { EOL } from "os"
+import { cmd } from "../cmd"
+
+export const StartupCommand = cmd({
+  command: "startup",
+  describe: "print startup timing",
+  builder: (yargs) => yargs,
+  handler() {
+    process.stdout.write(performance.now().toString() + EOL)
+  },
+})