Simplify telemetry to three game events

src/lib/server/db/schema.sql

@@ -39,8 +39,8 @@ CREATE TABLE IF NOT EXISTS servers (
     -- and resume from the same anchor when the server comes back.
     active_since     TEXT,                                -- ISO ts of last 0 -> >0 player transition
     inactive_since   TEXT,                                -- ISO ts of last >0 -> 0 player transition
-    game_started_at  TEXT,                                -- wall-clock ISO when we first saw a J; line for the current match cycle
-    game_ended_at    TEXT,                                -- wall-clock ISO when we first saw ExitLevel/ShutdownGame end it
+    game_started_at  TEXT,                                -- receipt time of the script's game_start
+    game_ended_at    TEXT,                                -- receipt time of the script's game_end
     game_cycle_key   TEXT,                                -- opaque marker for the currently-tracked cycle (the first J; line after the latest InitGame); lets us detect same-players game restarts
     created_at       TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now'))
 );
@@ -314,7 +314,8 @@ CREATE TABLE IF NOT EXISTS server_telemetry (
     server TEXT PRIMARY KEY REFERENCES servers(name) ON DELETE CASCADE,
     round INTEGER NOT NULL,
     players INTEGER NOT NULL,
-    received_at TEXT NOT NULL
+    received_at TEXT NOT NULL,
+    payload TEXT
 );
 -- Lifecycle history deliberately survives removal of the server registry row.
 CREATE TABLE IF NOT EXISTS server_deployments (