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
- V1 requirements: C4 docs, ADR, AGENTS.md, debug-log.md
- Design documents in docs/

packages/tui/test/util/model.test.ts

@@ -0,0 +1,9 @@
+import { describe, expect, test } from "bun:test"
+import { parse } from "../../src/util/model"
+
+describe("util.model", () => {
+  test("splits provider from a nested model identifier", () => {
+    expect(parse("provider/org/model")).toEqual({ providerID: "provider", modelID: "org/model" })
+    expect(parse("invalid")).toEqual({ providerID: "invalid", modelID: "" })
+  })
+})