fix(adapters): declare @archon/providers as workspace dep

CI's stricter package-resolution caught that @archon/adapters imports
@archon/providers/types (TokenUsage) without declaring the workspace
dependency. Locally bun resolved it transitively via @archon/core; CI's
clean install does not.

Author: Wirasm

bun.lock

@@ -19,6 +19,7 @@
     "@archon/git": "workspace:*",
     "@archon/isolation": "workspace:*",
     "@archon/paths": "workspace:*",
+    "@archon/providers": "workspace:*",
     "@octokit/rest": "^22.0.0",
     "@slack/bolt": "^4.6.0",
     "discord.js": "^14.16.0",