Fix retrait DB migration + emojis panel

- db.py: Ajout migration ALTER TABLE pour colonne client_negative_floor
  (correction du bug 'no such column' sur les bases existantes)
- panel.py: Tous les boutons du panel avec emojis
- panel.py: Correction TextSelect -> TextDisplay (panel crash)

utils/db.py

@@ -72,6 +72,11 @@ CREATE INDEX IF NOT EXISTS idx_institutions_guild ON institutions(guild_id);
 """
 
 
+MIGRATIONS = [
+    "ALTER TABLE banks ADD COLUMN client_negative_floor REAL DEFAULT 0.0",
+]
+
+
 async def get_db() -> aiosqlite.Connection:
     os.makedirs(os.path.dirname(DB_PATH), exist_ok=True)
     db = await aiosqlite.connect(DB_PATH)
@@ -79,5 +84,10 @@ async def get_db() -> aiosqlite.Connection:
     await db.execute("PRAGMA journal_mode=WAL")
     await db.execute("PRAGMA foreign_keys=ON")
     await db.executescript(SCHEMA)
+    for migration in MIGRATIONS:
+        try:
+            await db.execute(migration)
+        except Exception:
+            pass
     await db.commit()
     return db