Add RPC provider selector option in faucet page

[sudo-shashank]

Summary

The faucet currently hardcodes a single RPC endpoint per network (Glif). Users cannot switch providers when one is slow, rate-limited, or unavailable. This task adds a provider selector and refactors RPC usage so the UI and faucet controller share a reactive RpcContext.

Completion Criteria

• Define multiple RPC providers per network (Calibnet and Mainnet): Glif, Ankr, and Filfox
• Add an RPC provider selector on individual faucet pages, inline with the address input
• Wire FaucetController to use RpcContext for balance lookups, drips, and transaction confirmation polling
• Re-fetch balances and network info when the selected provider changes

Additional Links & Resources

[coderabbitai]

🔗 Related PRs

#311 - feat: increase calibnet global drip to 200x [merged]
#343 - Fix e2e test: Use a small drip amount in CI [merged]
#423 - Fix: Independent config for calibnet datacap wallet [merged]

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