Export partially-captured groups as stable

Stop treating partially-captured oldest timestamp groups (including Arc 10-pulls) as a special "incomplete" case. All decoded rows are now exported and marked with stable UIDs; the previous INCOMPLETE_* warnings and related console hint logic were removed. annotate_groups and annotate_arc_groups were simplified to always set uid_status="stable" and export_record=True, and arc_stability_warnings was deleted. CLI, live capture runner, console, tests, docs and mappings were updated to reflect the new behavior and to remove emission/handling of those informational warnings.

mappings/arc_miracle_box.json

@@ -27,6 +27,6 @@
   },
   "notes": [
     "Arc history is separate from Monopoly history.",
-    "Arc timestamp groups are 10-pull groups; an incomplete oldest group is still exported (stable prefix) with a warning."
+    "Arc timestamp groups are 10-pull groups; a partially captured oldest group is still exported (stable prefix)."
   ]
 }