Version 2.1.281 build details and internal refactors

What

• The built-in version is now 2.1.281, with build time 2026-09-23T02:22:43Z and git SHA 3e320108de6831eb996e9a3f7795152073cc0d0c.
• The version helper now also returns builtAt.
• The artifact tool's output gains a db_profiles section.
• The bookkeeping that counts MCP servers (external tool servers Claude Code connects to) now counts a second category.
• A new helper looks up permission rules by toolName and ruleContent.
• The rest is refactoring with the same behaviour: sorted-key JSON now goes through Fe.canonicalJson, a skipIf check and a tool-presence check moved into helpers, directory reading goes through the file-system layer, a detail string comes from a shared function, a hint-stripping step now takes a flag, one step passes a receiver along, and one argument changed from undefined to false, which behaves the same.
• Other changes are renamed internals and formatting in areas such as iTerm2 setup, agent summaries, plugin validation, the hooks API table, the message queue, the directory-sync watcher, headless sessions, vim input, the footer hint, settings descriptions, artifact publishing, CLI options, resume and hooks.

Why

Apart from the new db_profiles section and the MCP server count, these changes do not alter how Claude Code behaves.