Widen settings.description to TEXT; run seeders in CI

The dualpath_single_machine setting description is 257 chars but
settings.description was varchar(255). On strict MySQL 8 an over-length
insert is a hard error 1406 (Data too long), so `flask seed settings`
failed on a fresh install; older/relaxed MySQL truncated silently and
hid it. Widen the column to TEXT (matches value, already TEXT) via core
migration 7d26.

CI only ran `flask db upgrade` + plugin install, never the seeders, so it
missed this. Add a seed step to the migrations-mysql job so a seeded row
that violates a column constraint fails CI on strict MySQL 8 instead of
shipping.

migrations/versions/7d26_settings_description_text.py

@@ -0,0 +1,61 @@
+"""Widen settings.description to TEXT (was varchar(255))
+
+Seeded setting descriptions are explanatory sentences; some exceed 255 chars
+(e.g. dualpath_single_machine). On strict MySQL 8 an over-length insert is a
+hard error 1406, not a silent truncation, so `flask seed settings` failed on a
+fresh box. TEXT removes the ceiling and matches value, which is already TEXT.
+
+Idempotent guard on current column type; real downgrade back to varchar(255).
+
+Revision ID: 7d26_settings_description_text
+Revises: 7d25_drop_redundant_indexes
+Create Date: 2026-07-17
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = '7d26_settings_description_text'
+down_revision = '7d25_drop_redundant_indexes'
+branch_labels = None
+depends_on = None
+
+
+def _description_type(insp):
+    for c in insp.get_columns('settings'):
+        if c['name'] == 'description':
+            return str(c['type']).upper()
+    return None
+
+
+def upgrade():
+    bind = op.get_bind()
+    insp = sa.inspect(bind)
+
+    if 'settings' not in insp.get_table_names():
+        return
+    coltype = _description_type(insp)
+    if coltype is None or 'TEXT' in coltype:
+        return
+
+    op.alter_column('settings', 'description',
+                    existing_type=sa.String(length=255),
+                    type_=sa.Text(),
+                    existing_nullable=True)
+
+
+def downgrade():
+    bind = op.get_bind()
+    insp = sa.inspect(bind)
+
+    if 'settings' not in insp.get_table_names():
+        return
+    coltype = _description_type(insp)
+    if coltype is None or 'TEXT' not in coltype:
+        return
+
+    op.alter_column('settings', 'description',
+                    existing_type=sa.Text(),
+                    type_=sa.String(length=255),
+                    existing_nullable=True)