Feat/retire aimdb ws protocol

[lxsaah]

Retire aimdb-ws-protocol — every transport speaks AimX

Deletes the WebSocket-only wire protocol and converges the entire workspace on
the AimX-v3 envelope (aimdb-core::session::aimx). One codec, one error
mapping, one client demux — the WebSocket stack and the browser bridge now ride
the same session engine as UDS/serial/TCP and aimdb-client.

Implements design 047 (docs/design/047-retire-ws-protocol-converge-on-aimx.md).

Why

The workspace shipped two wire protocols for one feature. Every capability —
snapshots, acks, writes, queries, subscribe — existed twice, with two codecs and
two error vocabularies, plus a hand-rolled ~835-line browser demux duplicating
run_client. Both protocols already rode the same session engine, so the fork
was pure duplication.

Convergence removes a 353-line protocol crate, a 507-line codec, two error
mappings, and the browser demux, against a small additive AimX extension
(wildcard subscribe + two result-shape changes) that every transport now
inherits (CLI watch 'temp.#', MCP wildcard reads, future serial/TCP browsers).

What changed

Core (additive AimX extension)

• Wildcard / multi-record live subscribe. A pattern containing #/*
  matches the (builder-frozen) record set once at subscribe time, merges the
  matched records' update streams under one subscription id, and emits one
  snapshot per matched record on open.
• topic_match module — MQTT-style matching over dot-separated keys, shared
  by the core wildcard path and the WS fan-out bus.
• SubUpdate item type — subscription streams now carry
  { topic: Option<Arc<str>>, data, skipped } so each event names the concrete
  record that fired and threads buffer-lag counts through for drop detection.
• Wire additions: optional topic on event, sub on snap, an explicit
  subscribed ack frame (WS only; UDS/serial/TCP stay ack-implicit).
• Query/list result shapes: record.query → { records: [{topic, payload, ts}], total } (canonical QueryRecord row); RecordMetadata gains
  schema_type and entity.
• Version-gated hello — protocol bumped 2.0 → 3.0; an incompatible or
  version-less peer is refused at the handshake (RpcError::VersionMismatch).
• Loss accounting — buffer lag folds into skipped; the server pump does
  seq += skipped + 1; the client demux recovers loss as a seq shortfall.

WebSocket connector

• Speaks AimX on the transport (one codec blob per WS text frame — no extra
  framing). Dispatch converged on record.query / record.list.
• The fan-out bus carries (topic, payload) as Arc-shared updates; the
  per-connection codec envelopes each event (O(1) fan-out preserved).
• record.query falls back to the persistence-registered QueryHandlerFn when
  no custom handler is plugged in; record.list rows are stamped with schema
  names from the connector's StreamableRegistry.
• Removed: WsCodec + id↔topic maps, split_multi_topic, the pre-serialized
  Data-frame broadcast, with_raw_payload, ClientConfig::topic_routed_subs.

Browser bridge (aimdb-wasm-adapter::ws_bridge)

• Rewritten on run_client + ClientHandle over a web_sys::WebSocket-backed
  Connection/Dialer (single-threaded wasm Send/Sync wrappers). Reply and
  subscription correlation now exists exactly once, in core.
• JS API preserved: write, query, listTopics, onStatusChange, offline
  queue, and reconnect are all delegated to the engine.

Deletions

• aimdb-ws-protocol crate, WsCodec, protocol.rs shims, dead aimdb-client
  re-exports.

Breaking changes

• Wire protocol 2.0 → 3.0 — pre-3.x clients are refused at hello. Browser
  clients on the old ws-protocol wire must ship the rebuilt bridge; they fail
  closed against a 3.0 server.
• Removed builder knobs: with_raw_payload, ClientConfig::topic_routed_subs.
• record.query result shape changed from {values:[{record,value,stored_at}], count} to {records:[{topic,payload,ts}],total}.

Lands as one branch in a release already flagged protocol-breaking, one commit
per work item (no stacked PRs).

Testing

make check and make all green. New/updated coverage: AimX codec roundtrip
suite (frames + splice byte-for-byte), topic_match tests, topic_leaf
dual-separator, version-compatibility matrix, query_handler_shape,
UDS handshake_version, rewritten WebSocket e2e.rs (subscribe ack, wildcard
fan-out, late-join), and fan-out encode benchmarks.

Known limitations (accepted)

• Auto-subscribe under engine demux — server-seeded subscriptions carry
  server-chosen sub ids (counted down from u64::MAX); a run_client-based
  consumer drops events for ids it never issued, so engine clients (including the
  new bridge) subscribe explicitly. No user-visible change (the pro hub already
  subscribes by exact name).
• Dynamic record membership — wildcard matches are resolved once at subscribe
  time against the builder-frozen record set; MQTT-style late registration is
  deferred until core grows runtime registration.