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.

config/artemis.jsonc

@@ -110,8 +110,8 @@
       },
       "chunking": {
         "max_steps": 12,
-        "min_steps": 3,
-        "target_source_tokens": 2000,
+        "min_steps": 6,
+        "target_source_tokens": 6000,
         "model": "${env:OPENAI_MODEL:-mimo-v2.6-flash}",
         "max_chunks": 8
       },