port(smarm): track HEAD efbc254 — RFC 014/015 API sync

- gen_server rename (RFC 015, 3e31606): ServerRef/ServerCtx/ServerBuilder
  -> GenServerRef/GenServerCtx/GenServerBuilder across conn_actor,
  conn_registry, serve, pubsub, channels::session.
- type Timer = () on the three GenServer impls (RFC 015, 57eadb5);
  handle_timer/handle_idle/tick_every stay defaulted — opt-in later.
- Watcher and GenServerCtx are now generic over the server type: watcher
  fields typed Watcher<Table<M>> / Watcher<Registry<P, K>>; Registry's
  struct bounds strengthened to its GenServer impl bounds
  (P: Encode + Decode + Send + Sync + 'static, K: SessionKey) so the
  Watcher field's G: GenServer bound is satisfiable at the declaration.
- RFC 014 (a866e34) registry: register is (Name<M>, Sender<M>), self-only
  — a name is a typed messaging endpoint, not a pid tag. The
  introspection-only urus.server / urus.listener.{i} bindings are dropped
  rather than faked with unit channels; the whereis integration test is
  deleted; a proper messageable-name design is icebox'd in ROADMAP.md.
- Audit vs smarm 6c2b7e9 (queued messages dropped when Receiver drops):
  pubsub's prune-on-send-failure retain still holds — send Errs once
  receiver_alive is false, so a dropped rx prunes on next broadcast,
  exactly what subscriber_count's doc already promised. Freeing stranded
  Arc<M> broadcasts is strictly good. No change needed.
- The 7x E0283 in channels/mod.rs were cascade fallout of the generics
  changes; dissolved with the port, as discovery predicted.

Suite: 90 lib + 45 integration + 2 doc, green under default, smarm-trace,
phoenix, and all-features. 3 pre-existing clippy lints (conn.rs,
parser.rs, conn_actor.rs; clippy 1.97 strictness) deferred to a follow-up
chore commit to keep this diff pure.

src/pubsub.rs

@@ -58,7 +58,7 @@
 //! # Why there is no `register(name)` helper (yet)
 //!
 //! smarm's registry maps `name → Pid`, but a `Pid` cannot be turned back
-//! into a `ServerRef` (the ref *is* the inbox sender). A useful named
+//! into a `GenServerRef` (the ref *is* the inbox sender). A useful named
 //! lookup therefore needs either smarm support (registry-held senders)
 //! or a process-global type-erased map here — both against the grain of
 //! the ratified design. Deferred; pass the handle.
@@ -67,8 +67,8 @@ use std::collections::{HashMap, HashSet};
 use std::fmt;
 use std::sync::Arc;
 
-use smarm::gen_server::{self, GenServer, ServerCtx};
-use smarm::{channel, Down, Pid, Receiver, Sender, ServerRef, Watcher};
+use smarm::gen_server::{self, GenServer, GenServerCtx};
+use smarm::{channel, Down, Pid, Receiver, Sender, GenServerRef, Watcher};
 
 // ---------------------------------------------------------------------------
 // Public handle
@@ -92,7 +92,7 @@ impl std::error::Error for PubSubDown {}
 /// Payloads are broadcast as `Arc<M>`: one allocation per broadcast, not
 /// per subscriber.
 pub struct PubSub<M: Send + Sync + 'static> {
-    server: ServerRef<Table<M>>,
+    server: GenServerRef<Table<M>>,
 }
 
 impl<M: Send + Sync + 'static> Clone for PubSub<M> {
@@ -226,7 +226,7 @@ struct Table<M: Send + Sync + 'static> {
     /// retires the entry so a reused-slot pid (fresh generation) gets a
     /// fresh monitor.
     monitored: HashSet<Pid>,
-    watcher: Option<Watcher>,
+    watcher: Option<Watcher<Table<M>>>,
 }
 
 impl<M: Send + Sync + 'static> Table<M> {
@@ -240,8 +240,9 @@ impl<M: Send + Sync + 'static> GenServer for Table<M> {
     type Reply = Reply;
     type Cast = Cast<M>;
     type Info = ();
+    type Timer = ();
 
-    fn init(&mut self, ctx: &ServerCtx) {
+    fn init(&mut self, ctx: &GenServerCtx<Self>) {
         self.watcher = Some(ctx.watcher());
     }