feat: per-agent concurrency — claude: 1, gemini: 3, codex: 1

Co-Authored-By: Virgil <virgil@lethean.io>

config/agents.yaml

@@ -2,8 +2,6 @@ version: 1
 
 # Dispatch concurrency control
 dispatch:
-  # Maximum concurrent agent processes (0 = unlimited)
-  max_concurrent: 2
   # Default agent type when not specified
   default_agent: claude
   # Default prompt template
@@ -11,6 +9,12 @@ dispatch:
   # Workspace root (relative to this file's parent)
   workspace_root: .core/workspace
 
+# Per-agent concurrency limits (0 = unlimited)
+concurrency:
+  claude: 1
+  gemini: 3
+  codex: 1
+
 # Agent identities (which agents can dispatch)
 agents:
   cladius: