docs(link): the player-vendor marketplace (Protocol 3.0 §8)

Documents order 5b across the four repos, and records what building it changed
about §8 as designed.

- NEW website/MARKETPLACE.md — the operator guide: what the pages must say out
  loud and why, the privacy contract (the player's in-game Vendor Search toggle
  wins, and no admin setting overrides it), the Bridge.cfg knobs and how they
  trade against each other, and the measured sweep costs.
- INTEGRATION.md — catalog entry for vendor.listing / vendor.listing.remove with
  its six consumer gotchas, and the GET /market REST section (the sidecar's only
  paged read, and why it orders by serial rather than shop name).
- BACKEND_DESIGN.md — shard_vendors / shard_vendor_items, the routes, and the
  marketplace search as the only rate-limited public read.
- SHARD_VISIBILITY.md — why the market's fields default to Everyone (the in-game
  gump already shows exactly that set), why location is one setting covering
  four things, and why hiding the owner name without the owner id achieves
  nothing.
- PLAN.md — the amortized round-robin as the one sweep pattern the bridge did not
  previously have, and an update to §7's cliloc note: pushing name resolution to
  the plugin was never an option, because ServUO cannot read a modern client's
  compressed cliloc files either.
- v3.md §8.8 — the four things the build settled differently, chief among them
  that §8.1's FLAT location payload would have made Part A's pre-wired
  market.location rule inert, exactly like the characterName miss one part
  earlier.

Co-Authored-By: Claude <noreply@anthropic.com>

link/PLAN.md

@@ -284,6 +284,15 @@ Counts in `hello` are a live snapshot taken on the Core thread, not a cached val
 
 `Item.Name` is frequently `null`; the display name is `LabelNumber`, a cliloc id. **There is no `Data/Cliloc.enu` in this repo** — `BRIDGE_FINDINGS.md` §IV.4 is wrong about this. Cliloc data lives in the client install, which `DataPath` resolves to `D:\Games\Electronic Arts\Ultima Online Classic\`. Ship **both** `name` (when non-null) and `cliloc`, and resolve the number **on the website** against a cliloc map. That avoids a server-side dependency on the client directory.
 
+**Update (3.0).** That recommendation held, and the reason it had to hold turned out to be stronger
+than "avoids a dependency": **ServUO cannot resolve clilocs either.** Every current client ships its
+`Cliloc.*` files compressed, and the bundled `Ultima.StringList` reads only the older plain layout —
+so `VendorSearch.StringList` is null and `VendorSearch.GetItemName` returns `item.Name` on any modern
+shard. The in-game Vendor Search gump has the same gap, which is why `vendor.listing` never calls it.
+Pushing name resolution to the plugin was never an option. See [`v3.md`](v3.md) §8.6 and
+`docs/website/CLILOCS.md` for how the site gets a table instead (the operator converts one from their
+own client, once).
+
 ---
 
 ## 8. Corrections to `BRIDGE_FINDINGS.md`
@@ -327,6 +336,17 @@ leaderboards. `BridgePoints` is the widest read the bridge performs: ten of Serv
 keep a row for every character ever created, so it selects the top N in a single bounded pass rather
 than sorting, and runs on a deliberately slow 300 s interval.
 
+Also shipped: **`vendor.listing`** ([`v3.md`](v3.md) §8), `BridgeMarket.cs`, the shard-wide
+player-vendor index. It introduces the one sweep pattern the bridge did not previously have — an
+**amortized round-robin**. Every other sweep walks its whole collection per tick, which is fine for
+tens of houses or a fixed set of point systems and is not fine for a world of shops whose inventories
+recurse into containers. `BridgeMarket` inventories at most `MarketSweepBatch` vendors per tick from
+a persistent cursor, so the per-tick cost is bounded by the batch rather than by world size, and full
+coverage takes `ceil(vendors / batch) x MarketSweepSeconds`. Measured at **15.4 ms** for a cold tick
+of 25 vendors x 40 listings and **0.3 ms** in steady state (the per-vendor diff), on a shard of 209k
+items / 43k mobiles. It is also the first stream to honour a per-player privacy toggle: ServUO's own
+`PlayerVendor.VendorSearch` flag, so a shop hidden in game is hidden on the site.
+
 ### Config keys (`Config/Bridge.cfg`)
 
 ```ini
@@ -342,7 +362,8 @@ Read in `Configure()` via `Config.Get<T>("Bridge.<Key>", default)`. Key scope is
 
 The set above is the 1.0 sample, not the current one — every later phase added keys (sweep intervals
 for each board, the town-crier/news caps, the admin write plane, account provisioning, and 3.0's
-`RulesetEnabled` / `PublicConnectAddress` / `RulesetIncludeSchedule`, and the `Points*` block).
+`RulesetEnabled` / `PublicConnectAddress` / `RulesetIncludeSchedule`, and the `Points*` and `Market*`
+blocks).
 **`servuo-plugins/overlay/Config/Bridge.cfg`
 is the authoritative, commented list**; `BridgeConfig.cs` holds the defaults.