CLAUDE.md: load the Vikunja MCP schemas in one call (V-445)

The four schemas are deferred, so a session that looks them up on first use
spends four round trips on tools it always needs. One ToolSearch line at the
start covers them.

Also records the update_task quirk: a call carrying a description resets done
to false, so closing a task with a write-up takes two calls.

CLAUDE.md

@@ -341,6 +341,16 @@ Vikunja is the durable task store. A task holds the goal, the constraints and th
 assumption ledger. Work without a task id is work nobody can resume, so a session that
 has no id asks for one before it starts.
 
+The MCP tool schemas are deferred, so load the four you actually use in ONE call at the
+start of a session rather than one lookup per first use:
+
+```text
+ToolSearch("select:mcp__vikunja__list_tasks,mcp__vikunja__get_task_details,mcp__vikunja__create_task,mcp__vikunja__update_task")
+```
+
+`update_task` carrying a `description` resets `done` to false, so closing a task with a
+write-up takes two calls: the description, then `done: true`.
+
 ## Session workflow
 
 `~/.local/bin/task` owns the branch, the commit identity and the PR. One task, one