fix(web): Prevent default group card duplication

[itswcl]

Summary

• Filter display-only default card IDs and loading placeholders before persisting Default group reorder state.
• Reuse a case-insensitive default-card guard so polluted group payloads normalize correctly on the web.
• Add API-side filtering for reserved default card symbols in group responses/replacement plus regression coverage.

Test plan

• npm --prefix /Users/weilee/Desktop/fg-index/apps/web run lint
• npm --prefix /Users/weilee/Desktop/fg-index/apps/web run build
• npm --prefix /Users/weilee/Desktop/fg-index/apps/api-server test -- ticker-groups.test.ts
• npm --prefix /Users/weilee/Desktop/fg-index/apps/api-server run build
• Start Vite dev server and verify the app renders in headless Chrome

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