Remove static JSON files and seed step; migrate site settings to Postgres

All content (recipes + imprint/privacy settings) now lives exclusively in
Postgres. The app no longer requires a seed step on first deploy.

Changes:
- helpers.php: load_site_settings() returns defaults when site_settings
  table is empty instead of throwing DatabaseUnavailableException; removes
  legacy JSONB migration path
- data/recipes.json, data/site.json: deleted (content already in DB)
- scripts/db-seed.php: deleted (no longer needed)
- docker-compose.yml: remove RUN_DB_SEED env var and data/ volume mount
- docker/entrypoint.sh: remove RUN_DB_SEED seed block
- docs/COOLIFY.md: update deployment guide to reflect seedless workflow
- .claude/launch.json: add dev server configurations for preview tool

Fresh deploys now start with placeholder legal pages and an empty recipe
list; the admin fills in real content via /admin.php without any CLI step.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/schema.sql

@@ -68,3 +68,14 @@ CREATE TABLE IF NOT EXISTS recipe_steps (
 );
 
 CREATE INDEX IF NOT EXISTS idx_recipe_steps_slug_lang ON recipe_steps (recipe_slug, lang);
+
+CREATE TABLE IF NOT EXISTS site_settings (
+    section VARCHAR(32) NOT NULL CHECK (section IN ('imprint', 'privacy')),
+    lang CHAR(2) NOT NULL CHECK (lang IN ('en', 'de')),
+    setting_key VARCHAR(64) NOT NULL,
+    setting_value TEXT NOT NULL DEFAULT '',
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    PRIMARY KEY (section, lang, setting_key)
+);
+
+CREATE INDEX IF NOT EXISTS idx_site_settings_section_lang ON site_settings (section, lang);