feat: persist player-scoped assignments

server/migrations/0002_assignments.sql

@@ -0,0 +1,28 @@
+-- Restart-safe player-scoped assignment projections. The signed manifest and
+-- join authorisation are persisted only after the allocator/manifest gate has
+-- succeeded; clients still receive them only through an authenticated owner
+-- read.
+
+CREATE TABLE assignments (
+    match_id TEXT NOT NULL,
+    player_id TEXT NOT NULL,
+    allocation_id TEXT NOT NULL,
+    server_id TEXT NOT NULL,
+    slot INTEGER NOT NULL CHECK (slot BETWEEN 0 AND 5),
+    region TEXT NOT NULL CHECK (region IN ('EU', 'NA')),
+    client_build TEXT NOT NULL,
+    protocol_version INTEGER NOT NULL CHECK (protocol_version > 0),
+    transport TEXT NOT NULL CHECK (transport IN ('enet', 'steam_sdr')),
+    endpoint TEXT NOT NULL,
+    join_authorisation TEXT NOT NULL,
+    manifest_digest BYTEA NOT NULL,
+    expires_at TIMESTAMPTZ NOT NULL,
+    revision BIGINT NOT NULL DEFAULT 0 CHECK (revision >= 0),
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    PRIMARY KEY (match_id, player_id),
+    FOREIGN KEY (match_id, player_id) REFERENCES match_participants(match_id, player_id),
+    UNIQUE (match_id, slot)
+);
+
+CREATE INDEX assignments_player_expiry
+    ON assignments (player_id, expires_at);