fix(ci): resolve unit test failures and ensure build dependencies

- Mock `readRelays` in `tests/app-batch-fetch-profiles.test.mjs` to correctly reflect `profileMetadataService` prioritization logic, ensuring relay query count assertions match actual execution.
- Add missing `load` mock to `hashtagPreferences` in `tests/profile-modal-controller.test.mjs` to prevent `TypeError` during `handleAddHashtagPreference` test.
- Update `netlify.toml` to set `NODE_ENV = "development"` during build, ensuring `devDependencies` (required for `npm run build:css`) are installed.
- Verified all unit tests pass locally.
- Verified build configuration syntax.

Co-authored-by: PR0M3TH3AN <[email protected]>

netlify.toml

@@ -1,3 +1,6 @@
 [build]
   command = "npm run build"
   publish = "dist"
+
+[build.environment]
+  NODE_ENV = "development"