add sqlc, fix background img fetching

grpc-backend/sqlc/schema/schema.sql

@@ -0,0 +1,36 @@
+-- Beatmap Table
+CREATE TABLE IF NOT EXISTS Beatmap (
+    BeatmapId INTEGER DEFAULT 0,
+    Artist TEXT DEFAULT '?????',
+    ArtistUnicode TEXT DEFAULT '?????',
+    Title TEXT DEFAULT '???????',
+    TitleUnicode TEXT DEFAULT '???????',
+    Creator TEXT DEFAULT '?????',
+    Difficulty TEXT DEFAULT '1',
+    Audio TEXT DEFAULT 'unknown.mp3',
+    MD5Hash TEXT DEFAULT '00000000000000000000000000000000',
+    File TEXT DEFAULT 'unknown.osu',
+    RankedStatus TEXT DEFAULT 'Unknown',
+    LastModifiedTime DATETIME DEFAULT '0001-01-01 00:00:00',
+    TotalTime INTEGER DEFAULT 0,
+    AudioPreviewTime INTEGER DEFAULT 0,
+    BeatmapSetId INTEGER DEFAULT -1,
+    Source TEXT DEFAULT '',
+    Tags TEXT DEFAULT '',
+    LastPlayed DATETIME DEFAULT '0001-01-01 00:00:00',
+    Folder TEXT DEFAULT 'Unknown Folder',
+    UNIQUE (Artist, Title, MD5Hash, Difficulty)
+);
+
+CREATE INDEX IF NOT EXISTS idx_beatmap_md5hash ON Beatmap(MD5Hash);
+CREATE INDEX IF NOT EXISTS idx_beatmap_lastModifiedTime ON Beatmap(LastModifiedTime);
+CREATE INDEX IF NOT EXISTS idx_beatmap_title_artist ON Beatmap(Title, Artist);
+
+-- Collection Table
+CREATE TABLE IF NOT EXISTS Collection (
+    Name TEXT DEFAULT '',
+    MD5Hash TEXT DEFAULT '00000000000000000000000000000000'
+);
+
+CREATE INDEX IF NOT EXISTS idx_collection_name ON Collection(Name);
+CREATE INDEX IF NOT EXISTS idx_collection_md5hash ON Collection(MD5Hash);