Add Rust server

Owns the database, PIN rotation and all LiveKit token minting. Kiosk
registration, session-stable joins, admin auth, layouts, branding, media
uploads and the hosted installer script.

Claude-Session: https://claude.ai/code/session_01SS9F92jb51bMCRCKem6QtD

server/src/models.rs

@@ -0,0 +1,60 @@
+use serde::Serialize;
+use serde_json::Value;
+use sqlx::FromRow;
+
+#[derive(FromRow)]
+pub struct KioskRow {
+    pub id: String,
+    pub name: String,
+    pub location: String,
+    pub room_name: String,
+    pub status: String,
+    pub last_seen_at: Option<i64>,
+    pub created_at: i64,
+    pub metrics: Option<String>,
+    pub metrics_at: Option<i64>,
+}
+
+#[derive(Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct KioskView {
+    pub kiosk_id: String,
+    pub name: String,
+    pub location: String,
+    pub room_name: String,
+    pub status: String,
+    pub last_seen_at: Option<i64>,
+    pub created_at: i64,
+    pub metrics: Option<Value>,
+    pub metrics_at: Option<i64>,
+}
+
+impl From<KioskRow> for KioskView {
+    fn from(row: KioskRow) -> Self {
+        Self {
+            kiosk_id: row.id,
+            name: row.name,
+            location: row.location,
+            room_name: row.room_name,
+            status: row.status,
+            last_seen_at: row.last_seen_at,
+            created_at: row.created_at,
+            metrics: row
+                .metrics
+                .and_then(|raw| serde_json::from_str(&raw).ok()),
+            metrics_at: row.metrics_at,
+        }
+    }
+}
+
+pub const KIOSK_COLUMNS: &str =
+    "id, name, location, room_name, status, last_seen_at, created_at, metrics, metrics_at";
+
+pub const OFFLINE_AFTER_MS: i64 = 90_000;
+
+pub fn derive_status(last_seen_at: Option<i64>, now: i64) -> &'static str {
+    match last_seen_at {
+        Some(seen) if now - seen <= OFFLINE_AFTER_MS => "online",
+        _ => "offline",
+    }
+}