fix: Superforms SSR import from /server path and Prisma client version mismatch

- Import superValidate from sveltekit-superforms/server instead of default
  path to avoid pulling SuperDebug.svelte into SSR
- Upgrade @prisma/client to match prisma CLI version (7.2.0 -> 7.8.0)
  so generated client's query_compiler_fast_bg files exist at runtime
- Add regression test verifying superValidate works in server context
- Add regression test verifying generated Prisma client compiler imports
  reference real files

package.json

@@ -50,8 +50,8 @@
 		"vitest-browser-svelte": "^2.0.1"
 	},
 	"dependencies": {
-		"@prisma/adapter-pg": "^7.2.0",
-		"@prisma/client": "^7.2.0",
+		"@prisma/adapter-pg": "^7.8.0",
+		"@prisma/client": "^7.8.0",
 		"@tiptap/core": "^3.15.3",
 		"@tiptap/extension-color": "^3.27.3",
 		"@tiptap/extension-highlight": "^3.27.3",