Add game event support to the admin client

Everything on the admin GameScript channel so far has been request/reply.
This adds the other direction: subscribe_events() opens a push stream so a
bot can react to the game instead of polling it, consumed either by awaiting
wait_for_event() or via an on_event callback. Both see every event; an event
goes to at most one waiter, and unclaimed ones sit in a bounded buffer.

Sixteen kinds, from two sources. The engine raises no GameScript event for a
vehicle reaching a stop or cargo arriving, so vehicle_arrive, vehicle_depart
and cargo_waiting are synthesised by the bridge sampling state every
`interval` ticks and diffing against the previous sample -- which means a
stop shorter than the interval is never reported, and the first sample only
establishes a baseline. The rest (crashes, industries, towns, companies,
subsidies) are engine events forwarded verbatim. vehicle_lost,
vehicle_waiting_in_depot and vehicle_unprofitable are deliberately absent:
the engine raises those only for AI companies, so a GameScript can never
observe them.

The server-side half lives in the AdminBridge GameScript, which is not in
this repo -- docker/config is gitignored -- so it has to be updated
separately for any of this to work.

Also repoints the scheduled-dispatch E2E test at a dedicated vehicle
(DISPATCH_VEHICLE_ID). It had been silently skipping because vehicle 7
carries a hand-built annual dispatch schedule, which left eight dispatch
methods unverified end to end while check_public_calls.py reported them
green off static analysis of the call sites.

Co-Authored-By: Claude <[email protected]>

README.md

@@ -17,6 +17,7 @@ A high-performance, Object-Oriented Python client for OpenTTD servers, specifica
 - **Station Listing:** Enumerate stations via the Admin GameScript channel with `list_stations()`.
 - **Station Cargo Snapshots:** `OpenTTDAdminClient.get_station()` returns a station's live per-cargo state from the running game — both the **real-time** amount waiting and the **planned** flow through the cargodist link graph — over the AdminBridge GS (stock GameScript API, no server patch needed).
 - **Cargo Flow Breakdown:** `OpenTTDAdminClient.get_station_cargo()` breaks one cargo type down by **source station** and **next hop** (routing destination) for both waiting (real-time) and planned amounts, with optional `from_station`/`via_station` filters.
+- **Game Events:** react to the game instead of polling it — `subscribe_events()` streams events over the AdminBridge GS as they happen: a vehicle reaching or leaving a stop (`vehicle_arrive`/`vehicle_depart`, with dwell time and cargo aboard), a station's waiting cargo changing (`cargo_waiting`), plus crashes, industries opening/closing, towns, companies and subsidies. Consume them with `await wait_for_event()` or an `on_event` callback; filter by kind, company, vehicle, station or cargo.
 
 ## 🛠 Setup
 
@@ -81,4 +82,5 @@ For detailed instructions on E2E testing and coverage reports, see the [Testing
 - [Architecture & Design](docs/ARCHITECTURE.md)
 - [Protocol Internals (PAKE/Encryption)](docs/PROTOCOL.md)
 - [Vehicle Timetables Usage Guide](docs/TIMETABLES.md)
+- [Game Events Usage Guide](docs/EVENTS.md)
 - [Contributor Guide](docs/CONTRIBUTING.md)