feat(server): lossy avatar thumbnails, gzip upload and separate avatar endpoints

server/src/WebDrop.Storage/SqliteChannelStore.cs

@@ -37,6 +37,7 @@ public sealed class SqliteChannelStore : IResourceStore, IDisposable
         Exec(_writeConn, "DELETE FROM channel_join_denials WHERE target LIKE 'endpoint:%';");
         // v7: 设置里的成员人数上限由 seats 改名为 max_members,迁移已有频道的设置 JSON(幂等)
         Exec(_writeConn, "UPDATE channels SET settings = json_remove(json_set(settings, '$.max_members', json_extract(settings, '$.seats')), '$.seats') WHERE json_extract(settings, '$.seats') IS NOT NULL AND json_extract(settings, '$.max_members') IS NULL;");
+        try { Exec(_writeConn, "ALTER TABLE channel_avatars ADD COLUMN thumb TEXT;"); } catch (SqliteException) { /* 新建的表或已经迁移过 */ }
         // Additive table: retain the running v2 database and its existing channel data.
         Exec(_writeConn, """
             CREATE TABLE IF NOT EXISTS channel_key_packages (
@@ -46,7 +47,7 @@ public sealed class SqliteChannelStore : IResourceStore, IDisposable
             CREATE INDEX IF NOT EXISTS ix_channel_keys_username ON channel_key_packages(username);
             CREATE TABLE IF NOT EXISTS workspace_structures (space_id BLOB PRIMARY KEY, state TEXT NOT NULL) WITHOUT ROWID;
             CREATE TABLE IF NOT EXISTS workspace_crypto (space_id BLOB PRIMARY KEY, state TEXT NOT NULL) WITHOUT ROWID;
-            CREATE TABLE IF NOT EXISTS channel_avatars (space_id BLOB PRIMARY KEY, avatar TEXT NOT NULL) WITHOUT ROWID;
+            CREATE TABLE IF NOT EXISTS channel_avatars (space_id BLOB PRIMARY KEY, avatar TEXT NOT NULL, thumb TEXT) WITHOUT ROWID;
             """);
     }
 
@@ -508,12 +509,13 @@ public sealed class SqliteChannelStore : IResourceStore, IDisposable
             Run("DELETE FROM channel_join_denials WHERE channel_id=@c", ("@c", key));
         }
 
-        public string? GetChannelAvatar(Id16 id) => Scalar("SELECT avatar FROM channel_avatars WHERE space_id=@c", ("@c", id.ToArray())) as string;
+        public string? GetChannelAvatar(Id16 id, bool thumb) =>
+            Scalar(thumb ? "SELECT COALESCE(thumb, avatar) FROM channel_avatars WHERE space_id=@c" : "SELECT avatar FROM channel_avatars WHERE space_id=@c", ("@c", id.ToArray())) as string;
 
-        public void SetChannelAvatar(Id16 id, string? avatar)
+        public void SetChannelAvatar(Id16 id, string? avatar, string? thumb)
         {
             if (avatar is null) Run("DELETE FROM channel_avatars WHERE space_id=@c", ("@c", id.ToArray()));
-            else Run("INSERT INTO channel_avatars (space_id, avatar) VALUES (@c,@a) ON CONFLICT(space_id) DO UPDATE SET avatar=excluded.avatar", ("@c", id.ToArray()), ("@a", avatar));
+            else Run("INSERT INTO channel_avatars (space_id, avatar, thumb) VALUES (@c,@a,@t) ON CONFLICT(space_id) DO UPDATE SET avatar=excluded.avatar, thumb=excluded.thumb", ("@c", id.ToArray()), ("@a", avatar), ("@t", (object?)thumb ?? DBNull.Value));
         }
 
         public IReadOnlyList<Id16> ListExpiredChannels(long now, int limit) =>