MCP `fleet`: query and act with dry-run by default #450

Tool fleet {query, action?, apply?} returning the same preview/receipt JSON as the API; apply requires rw and an explicit apply:true. Tests.

Part of #445.

Parked by the crew: the run ended without a pull: declined: #450 asks for an MCP fleet tool that returns "the same preview/receipt JSON as the API", and that API isn't in the repository yet. There is no src/ or test/ code for a fleet query parser (#446)

Parked by the crew: the run ended without a pull: declined: #450 asks for an MCP fleet tool that returns "the same preview/receipt JSON as the API". That API is not on main (3f03bf7) or on this branch.

Parked twice; deferred behind the Later gate #595 (umbrella #594): the MCP fleet tool serves no pillar now. Nothing is dropped; the owner moves it out by unlinking it from the gate. Start it fresh from main when it comes back.

Released from Later to use the week's subscription: Behind pace: 75% of the week left with 20% of its time gone, reset 2026-11-15 02:00 UTC, burning 0% an hour against 0.5% allowed; speeding up to 5 of 5 slots and releasing the next issue.

Parked by the crew: the check stayed red through 2 automatic tries (pull #10182 closed; its branch torque/450-mcp-fleet-query-and-act-with-dry-run-by at aa02af6ef5ab keeps the work so far). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.