fix: correct 2023-03-21 client wire contracts across the API and notify surfaces

Audits every route the March-2023 client can call against what this server
actually serves, and fixes the defects that were breaking gameplay. Adds
docs/recroom-2023-client-api-complete.md as the reference: ~500 route
literals across 13 subsystems, with verb, request/response shape, and a
per-subsystem diff. 315 defects catalogued; the ones fixed here are listed
in its "Already fixed" table.

Path coverage was never the problem — 465 of 506 routes already had
handlers. The failures were in shape, and they cluster into four causes:

- Wrong verb. The verb is a BestHTTP.HTTPMethods ordinal (GET=0 .. PATCH=5),
  confirmed from that enum's static constructor. Routes registered POST-only
  while the client PUTs returned 405, which made room consumables neither
  buyable nor consumable and blocked every room-key edit.
- Bare scalar wrapped in an object. The client reads `1000`, not
  `{"Limit":1000}`; the issuing method signature says which. Wrapping makes
  the deserializer throw and the feature dies silently.
- [FromBody] vs form-urlencoded. The client sends nearly every write as form
  data, which an [ApiController] action bound [FromBody] rejects with 415
  before the handler runs. This alone broke all 13 club member-management
  endpoints. Adds Binding/FormOrJsonModelBinder so this is fixed once.
- Notify dispatch keys. Both enum overloads of the client's RegisterHandler
  lower the id via Int32.ToString() and register only that numeric key, and
  lookup is a case-sensitive TryGetValue that returns silently on a miss. We
  were sending the enum NAME for most ids, so friend-request updates, forced
  logout, maintenance broadcasts, live balance and consumable updates, and
  invention moderation pushes all evaporated with no error anywhere.

Notable behavioural bugs fixed:

- Editing a club announcement deleted it: PUT was a third binding on the
  delete handler. Split apart, and the missing create route added.
- leaderboard/CheckAndSetStat did not exist. The 2023 client has no SetStat
  literal at all, so every leaderboard score it wrote was discarded.
- Setting a club clubhouse cleared it: the handler read roomId from the query
  while the client sends it in the body, then wrote the resulting null.
- Club join requests were inverted (the enum is Open=0, InviteOnly=1,
  AskToJoin=2), so ask-to-join clubs rejected everyone and invite-only clubs
  quietly admitted them.
- Room bans were pushed as id 24, for which the client registers no handler;
  they now go out as ModerationKick with IsBan, so the ban takes effect
  immediately instead of at next login.
- Room-key ownership queries answered for the wrong player, and "has anyone
  bought this key" asked "did I buy it" — always false for the creator.

Also persists settings that were previously acknowledged and dropped
(playlist accessibility/restrictions/level-voting/warning, per-player status
visibility, VR movement mode and avoid-juniors, custom room codes), which is
what the new columns in the migration are for.

One test asserted the old nested PriceAndCurrency response shape; the
client's consumable formatter has no such key and reads Price and
PurchaseCurrencyId flat, so the test was corrected alongside the handler.

docs/architecture.md

@@ -5,8 +5,10 @@ before you touch code; it explains layout, request flow, the design
 patterns that look weird in isolation, and where to start.
 
 For deployment, see [`deploy.md`](deploy.md). For wire-protocol
-reverse-engineering deliverables, see the `recroom-2020-client-*`
-files in this folder.
+reverse-engineering deliverables, see
+[`recroom-2023-client-api-complete.md`](recroom-2023-client-api-complete.md)
+(March-2023 client) and the `recroom-2020-client-*` files in this folder
+(December-2020 client).
 
 ---
 
@@ -253,6 +255,23 @@ client-side endpoints, DTOs, and request expectations extracted from
 the same decompile. They're the ground truth when a controller needs
 a new endpoint.
 
+[`docs/recroom-2023-client-api-complete.md`](recroom-2023-client-api-complete.md)
+is the equivalent for the March-2023 client, and additionally carries a
+per-subsystem diff of client expectation against current server behaviour.
+Three things account for nearly every defect it catalogues, so check all
+three whenever you touch a 2023 endpoint:
+
+- **The verb.** It is a `BestHTTP.HTTPMethods` ordinal in the disassembly
+  (GET=0, HEAD=1, POST=2, PUT=3, DELETE=4, PATCH=5). A route registered
+  under the wrong verb is a 405 the client reports as a generic failure.
+- **Scalar vs object.** Many endpoints return a BARE scalar — the client
+  reads `1000`, not `{"Limit":1000}`. Wrapping it makes the deserializer
+  throw and the feature fails silently.
+- **The body encoding.** The client sends nearly every write as
+  `application/x-www-form-urlencoded`. An action bound with `[FromBody]`
+  under `[ApiController]` rejects that with 415 before the handler runs.
+  Use `Binding/FormOrJsonModelBinder` rather than hand-rolling a reader.
+
 ---
 
 ## Database story