fix: ease onboarding with startup warnings and doc corrections

- Warn at startup when quest files are missing (clients crash without
  them) and point users to the download link
- Fix Host config description: it's the advertised IP, not a bind
  address — 0.0.0.0 was wrong advice
- Load bundled schemas (shops, events, gacha) in Docker init so new
  users get working demo data out of the box
- Renumber duplicate patch schema 28 → 32 to resolve numbering
  collision
- Fix patch schema example filename to use hyphens matching actual
  files

schemas/patch-schema/32-guild-posts-soft-delete.sql

@@ -0,0 +1,6 @@
+BEGIN;
+
+-- Add soft-delete column to guild_posts, matching the pattern used by characters and mail tables.
+ALTER TABLE guild_posts ADD COLUMN IF NOT EXISTS deleted boolean DEFAULT false NOT NULL;
+
+COMMIT;