feat: add official Codex skill and harden task execution

Install and update artemis-use with task diagnostics and plugin guidance. Preserve cross-device file receipts, review canonical reports, guard stage transitions and reduce small history summaries. Improve exploration lifecycle, request recovery and browser live connections.

artemis/memory/chunking.py

@@ -167,6 +167,10 @@ def build_action_ledger(
         user_line = injected_instruction_line(step)
         if user_line:
             lines.append(user_line)
+        from artemis.plugins.delivery import step_attachment_receipts
+
+        if receipt := step_attachment_receipts(step):
+            lines.append(f"  Runtime file receipts (storage only): {receipt}")
     return "\n".join(lines)
 
 
@@ -899,8 +903,8 @@ class HistoryChunkManager:
 
         cc = chunking_config
         self._max_steps = int(getattr(cc, "max_steps", 12) or 12)
-        self._min_steps = max(1, min(self._max_steps, int(getattr(cc, "min_steps", 3) or 3)))
-        self._target_source_tokens = int(getattr(cc, "target_source_tokens", 2000) or 2000)
+        self._min_steps = max(1, min(self._max_steps, int(getattr(cc, "min_steps", 6) or 6)))
+        self._target_source_tokens = int(getattr(cc, "target_source_tokens", 6000) or 6000)
         self._model_name = getattr(cc, "model", None) or settings.OPENAI_MODEL
         self._max_chunks = int(getattr(cc, "max_chunks", 8) or 8)
         # None uses max_chunks as the era cap.