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/

patches/pacote@21.5.0.patch

@@ -0,0 +1,18 @@
+diff --git a/lib/git.js b/lib/git.js
+index 000ee9fc..a2a6cbb7 100644
+--- a/lib/git.js
++++ b/lib/git.js
+@@ -254,8 +254,11 @@ class GitFetcher extends Fetcher {
+           resolved: this.resolved,
+           integrity: null, // it'll always be different, if we have one
+         }).extract(tmp).then(() => handler(`${tmp}${this.spec.gitSubdir || ''}`), er => {
+-          // fall back to ssh download if tarball fails
+-          if (er.constructor.name.match(/^Http/)) {
++          // fall back to clone if the tarball download fails due to an
++          // HTTP error or if the response is not a valid tarball (e.g.
++          // a hosted provider returning an HTML sign-in page with 200)
++          if ((typeof er.statusCode === 'number' && er.statusCode >= 400) ||
++              /^TAR_/.test(er.code)) {
+             return this.#clone(handler, false)
+           } else {
+             throw er