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/

patches/@npmcli%2Fagent@4.0.2.patch

@@ -0,0 +1,13 @@
+diff --git a/lib/agents.js b/lib/agents.js
+index 45ec59c4c13757379095131c4f0a5ea6f7284f45..0763b031e355a755ec6a26f98461aa3f63b8339b 100644
+--- a/lib/agents.js
++++ b/lib/agents.js
+@@ -32,7 +32,7 @@ module.exports = class Agent extends AgentBase {
+   }
+ 
+   get proxy () {
+-    return this.#proxy ? { url: this.#proxy } : {}
++    return this.#proxy ? { url: this.#proxy.toString() } : {}
+   }
+ 
+   #getProxy (options) {