chore: add changeset for API mode removal

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: him0

.changeset/remove-api-mode.md

@@ -0,0 +1,7 @@
+---
+"@him0/freee-mcp": minor
+---
+
+Remove API mode, keep client mode only
+
+BREAKING CHANGE: `freee-mcp api` subcommand has been removed. The server now only operates in client mode (HTTP method sub-commands). Use `freee-mcp` or `freee-mcp client` to start the server.