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/test/fixture/db.ts

@@ -0,0 +1,11 @@
+import { rm } from "fs/promises"
+import { Database } from "@opencode-ai/core/database/database"
+import { disposeAllInstances } from "./fixture"
+
+export async function resetDatabase() {
+  await disposeAllInstances().catch(() => undefined)
+  const dbPath = Database.path()
+  await rm(dbPath, { force: true }).catch(() => undefined)
+  await rm(`${dbPath}-wal`, { force: true }).catch(() => undefined)
+  await rm(`${dbPath}-shm`, { force: true }).catch(() => undefined)
+}