docs(roadmap,readme): v0.6 complete — record outcomes and deviations

Marks the three v0.6 items done with their hashes and the load-bearing
deviations: two-class lock order replacing the strict leaf rule, the
registry as a bimap with name_of and without send_by_name (no per-pid
mailbox to send to), and call_timeout built on recv_timeout instead of
monitor machinery. Adds the Leaf -> Channel order to the standing
invariants; README module table picks up recv_timeout, call_timeout,
and the registry row.

README.md

@@ -21,14 +21,15 @@ convenience wrapper around `runtime::init(Config::exact(1)).run(f)`.
 | `pid`        | `(index, generation)` PIDs; stale handles are detectable, not silent   |
 | `actor`      | Trampoline + `catch_unwind` boundary at the actor entry point          |
 | `scheduler`  | Run queue, slot table, spawn/join, parking, idle path                  |
-| `channel`    | Unbounded MPSC channel; `recv` parks the actor                         |
+| `channel`    | Unbounded MPSC channel; `recv` parks the actor; `recv_timeout` bounds it |
 | `mutex`      | `Mutex<T>` with mandatory timeout; FIFO waiters; parks the green thread |
 | `timer`      | Min-heap of `(deadline, reason)`; `Sleep` and `WaitTimeout` reasons    |
 | `io`         | `block_on_io` for blocking work; `wait_readable`/`wait_writable` + `read`/`write` via epoll |
 | `supervisor` | `Signal::Exit`/`Panic`/`Stopped` funnelled to a parent; `OneForOne`/`OneForAll`/`RestForOne` strategies + restart-intensity cap |
 | `monitor`    | `monitor(pid)` → `Monitor { id, target, rx }`; one-shot `Down` via `rx`; `demonitor(&m)` tears one registration down; unidirectional death notice |
 | `link`       | bidirectional `link`/`unlink`; abnormal death propagates (cooperative stop, or an `ExitSignal` message under `trap_exit`) |
-| `gen_server` | `call` (sync request-reply) / `cast` (async) over one inbox; `ServerRef` + `init`/`terminate` hooks; server-down via channel closure |
+| `gen_server` | `call`/`call_timeout` (sync request-reply) / `cast` (async) over one inbox; `ServerRef` + `init`/`terminate` hooks; server-down via channel closure |
+| `registry`   | `register`/`whereis`/`name_of`: name ↔ pid bimap; lazy generation-checked cleanup |
 
 ## Quick taste