fix: control port needs a per-launch token; MCP tool annotations tell the whole truth (#205) (#901)

solidcraft --control PORT writes a random per-launch token to a user-only file (<data>/control/PORT.token; 0700/0600 on Unix, icacls on Windows; SOLIDCRAFT_CONTROL_TOKEN overrides) and refuses any connection whose first request lacks it. mcp --connect, the demo and packaging smoke clients send it. MCP execute/batch/open/save/export/screenshot are annotated destructive and open-world, new_design destructive. Docs: control-protocol.md, mcp.md, AGENTS.md, pending release note in releasing.md.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

AGENTS.md

@@ -122,7 +122,10 @@ before the draft is verified.
 ## Running and looking at the app
 - `cargo run --release -p solidcraft -- --sample --control PORT` (sample design + control channel).
   Pick a free port. Without a display, run it under `Xvfb :99` with `DISPLAY=:99`.
-- Drive it with JSON lines on `127.0.0.1:PORT` (see `docs/control-protocol.md`):
+- Drive it with JSON lines on `127.0.0.1:PORT` (see `docs/control-protocol.md`). The first
+  request on a connection carries the launch's token as `"token"`: read it from
+  `~/.local/share/solidcraft/control/PORT.token`, or start the app with
+  `SOLIDCRAFT_CONTROL_TOKEN=$(openssl rand -hex 32)` and send that.
   - `{"id":1,"method":"engine.execute","params":{"command":"solid.extrude","params":{"distance":20}}}`
   - `{"id":2,"method":"ui.start","params":{"command":"sketch.create"}}` then `ui.click {x, y}`
   - `{"id":3,"method":"ui.screenshot","params":{"path":"/tmp/shot.png"}}` then read the PNG.