Claude collector: attribute pi usage by provider, not api prefix (#6655)

Pi/omp sessions kept falling into the Claude record when the api
field merely started with 'anthropic'. Kimi and other providers that
speak the anthropic-messages protocol (kimi-coding) were therefore
charged against Claude Code, showing k3 buckets under a Claude tab
even for a user without a Claude login.

Match the codex collector's provider-only attribution: only sessions
whose provider is exactly 'anthropic' count toward Claude usage.

Add a test proving a kimi-coding session sharing the
anthropic-messages api does not land in the Claude record.

Co-authored-by: Luca <luca@itwasarch>

bin/omarchy-agent-usage-claude

@@ -374,8 +374,7 @@ def scan_pi_usage(max_age_seconds: float) -> dict[str, Any] | None:
               if entry.get("type") != "message" or message.get("role") != "assistant":
                 continue
               provider = str(message.get("provider") or "")
-              api = str(message.get("api") or "")
-              if provider != "anthropic" and not api.startswith("anthropic"):
+              if provider != "anthropic":
                 continue
               unique_key = f"{path}:{entry.get('id') or line_number}"
               if unique_key in seen: