Code mode: enforce per-plan gating (saved-tool caps + inline Team+) #1446

The code-mode plan gating agreed on 2026-10-31 was scaffolded but not enforced: checkCanCreateCodeTool only capped the Cloud trial and returned early on self-hosted, and inline code was gated by role only (ADMIN), with no plan check.

Build it, numbers in the backend (not the licence site): a code-mode-quotas.ts mirroring file-search-quotas.ts, so existing keys need no reissue. An Enterprise contract can still override per key via features.maxCodeTools.

• Saved code tools, per plan (Cloud + self-hosted): Community 3 / Starter 5 / Team 20 / Business 20 / Enterprise unlimited. Unknown/no plan → Community. Enforced in LicenseGuardService.checkCanCreateCodeTool at creation time.
• Inline code (code_execute / code_propose_tool): Team and above only. Enforced where the MCP endpoint exposes it (resolveInlineCode), on top of the per-server codeMode and the inlineCode role capability.

No schema change. Off by default everywhere. Writes / definer / shared-endpoint exposure stay Enterprise/admin as before. Per-tier audit retention and Cloud monthly run quotas are out of scope here (operational / separate).