feat: the first pages, and what a browser walk found behind them

Phase 4. `/rust` is the server list and the module's landing page (D12);
`/rust/servers/:id` is one server with four tabs — feed, leaderboard, who is
on, wipes (D13). Everything selectable lives in the URL, so any view of the
page is a link. The feed and the presence list poll every twenty seconds while
the tab is visible and not at all when it is not (D14); the leaderboard and the
wipe list load once. `site.footer.status` is filled with a live server and
player count (D15).

Nothing on these pages calls a game server. Every field comes from this
module's own tables, which is what the phase criterion is about: the site
renders the last thing each server said while every server is off.

Walking that criterion in a browser against a live rig found four defects, two
of them already shipped in phase 3:

  * An unreachable refresh called `putState` — the whole-row write — with two
    fields, so a host that rebooted lost its hostname, map, size, seed and wipe
    id. The list then read "Offline" with nothing beside it, which is not "here
    is what we know" but "we have never heard of it". `markUnreachable` now
    moves three columns and mentions no others.
  * "Last reported" read `updated_at`, which a FAILED poll writes too — so an
    offline server claimed it had reported just now, every thirty seconds, for
    as long as it stayed down. `last_seen_at` is the new column, moved only by a
    frame that arrived.
  * Feed rows showed a bare time of day, so three events from six weeks ago all
    read as this afternoon once the feed was filtered to a past wipe.
  * `/rust/servers/typo` rendered core's ErrorState under its own heading and
    read "No such server / Something went wrong", sending a reader who mistyped
    a URL looking for an outage.

Also: a detail route (`GET …/servers/:id`), because it is the only route under
that path that can say a server does not exist — the other four answer an empty
list for an id nobody configured, and each of those is a good answer to its own
question.

`useAsync` cannot poll: it blanks its data on every dependency change, so a
twenty-second refresh built on it would clear the killfeed and re-fill it four
times a minute. `hooks/usePolled.js` is the module's own, invisible when it
succeeds and keeping the rows when it fails.

The client test fake was *nearly* core — it prefixed routes without stripping
the trailing separator, so the first module to register an index route failed
the nav check for a link that works in a browser. It now copies core's line
character for character.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016wDDVXWMDz82WqE1i969r4

swagger-fragment.json

@@ -196,6 +196,37 @@
         }
       }
     },
+    "/api/v1/public/rust/servers/{id}": {
+      "get": {
+        "tags": [
+          "Public · Rust"
+        ],
+        "summary": "One Rust server",
+        "description": "The same shape the list answers with, for one server, and a `404` when there is no such server or an operator has disabled it. The detail page needs the difference: every other route under this path answers an empty list for an id that does not exist, because an unknown server genuinely has no events and nobody online.",
+        "parameters": [
+          {
+            "name": "id",
+            "in": "path",
+            "required": true,
+            "schema": {
+              "type": "string"
+            },
+            "description": "The server’s slug"
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "The server"
+          },
+          "404": {
+            "description": "No such server, or it is disabled"
+          },
+          "500": {
+            "description": "Internal Server Error"
+          }
+        }
+      }
+    },
     "/api/v1/public/rust/servers/{id}/events": {
       "get": {
         "tags": [