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/tool/__snapshots__/tool.test.ts.snap

@@ -0,0 +1,9 @@
+// Bun Snapshot v1, https://bun.sh/docs/test/snapshots
+
+exports[`tool.ls basic 1`] = `
+"packages/opencode/test/fixtures/example/
+  broken.ts
+  cli.ts
+  ink.tsx
+"
+`;