add multiple dictionary API providers with automatic fallback mechanism

[Suke2004]

Description:
The extension currently depends solely on dictionaryapi.dev. If it fails, the extension becomes nonfunctional. Add multiple API sources with fallback logic to improve reliability.

🧩 Files to modify:
public/content/content.js, public/popupp1.js, src/components/DictionaryTooltip.tsx

✅ Acceptance Criteria:

• Integrate at least two secondary dictionary APIs.
• Implement fallback logic on primary API failure.
• Cache successful responses for faster lookups.
• Add optional offline mode with last known definitions.

[Nilakshhh]

Can this be assigned to me? thankyou