refactor: clean up architecture and add error page

- Remove unused adapters (adapter-auto, adapter-cloudflare-workers)
- Update compatibility_date to 2025-01-01
- Extract generateInstallScript to lib/server/install-script.ts
- Extract PRESET_PACKAGES to shared lib/presets.ts
- Add +error.svelte for 404/500 pages
- Improve deploy workflow migration logging

Author: fullstackjam

.github/workflows/deploy.yml

@@ -32,8 +32,13 @@ jobs:
         run: |
           for migration in migrations/*.sql; do
             if [ -f "$migration" ]; then
-              echo "Applying migration: $migration"
-              wrangler d1 execute openboot --remote --file="$migration" || true
+              echo "::group::Migration: $migration"
+              if wrangler d1 execute openboot --remote --file="$migration" 2>&1; then
+                echo "Migration applied successfully"
+              else
+                echo "Migration skipped (already applied or error)"
+              fi
+              echo "::endgroup::"
             fi
           done