fix: provenance dates on unverified fields and breakdown separator spacing

- compat.unverified messages now correctly append (as of YYYY-MM-DD)
  for Codex and Cursor agents (was checking capitalized names against
  lowercase COMPAT_MATRIX keys)
- --explain-score breakdown uses ' · ' separator between dimensions
  instead of '· ' (missing leading space)

Author: Brad Kinnard

src/skillcheck/cli.py

@@ -130,7 +130,7 @@ def _format_text(
                         "specificity": (bd.get("specificity", 0), 15),
                         "length": (bd.get("length", 0), 10),
                     }.items()]
-                    lines.append(f"{'':>12}{'· '.join(parts)}")
+                    lines.append(f"{'':>12}{' · '.join(parts)}")
 
     # summary
     total = len(results)

src/skillcheck/rules/compat.py

@@ -114,9 +114,9 @@ def check_unverified_fields(skill: ParsedSkill) -> list[Diagnostic]:
             agents_str = ", ".join(sorted(unknown_agents))
             # Provenance: attach dates for agents with "unknown" status
             date_parts = []
-            if "Codex" in agents_str:
+            if "codex" in [a.lower() for a in unknown_agents]:
                 date_parts.append(f"Codex: {_CLAUDE_DATA_DATE}")
-            if "Cursor" in agents_str:
+            if "cursor" in [a.lower() for a in unknown_agents]:
                 date_parts.append(f"Cursor: {_CURSOR_DATA_DATE}")
             date_suffix = ""
             if date_parts: