feat(library): let auditors correct game data

An AUDITOR corrects name, header image, speedrun link, moods, endless and genres of a game for every user (V20 game_correction, PUT/DELETE /api/library/games/{appid}/corrections/{field}). The value is also written into the cached row, so reads stay unchanged; the Steam sync, the image repair, the IGDB add and the mood and speedrun upserts skip corrected fields. SteamGame gets @DynamicUpdate so a sync no longer writes back columns it did not change.

src/main/resources/db/migration/V20__game_correction.sql

@@ -0,0 +1,13 @@
+-- An auditor's correction of shared game data. The value is also written into the cached row (steam_game,
+-- game_speedrun, game_mood), so reads need no join; the refresh writers skip a corrected field. value and
+-- source_value are JSON (a string, a string list, a boolean or null); source_value is what the source had at the
+-- first correction, written back by "back to source".
+CREATE TABLE game_correction (
+    appid        BIGINT      NOT NULL,
+    field        VARCHAR(16) NOT NULL,
+    value        TEXT,
+    source_value TEXT,
+    corrected_by BIGINT      NOT NULL,
+    corrected_at TIMESTAMPTZ NOT NULL,
+    PRIMARY KEY (appid, field)
+);