frontend features

[Marvell69]

Closes #1449
Closes #1450
Closes #1451
Closes #1452

Implemented the requested frontend features:

• Webhook management page, registration/edit modal, secret copy/regeneration, toggling, deletion, test delivery, and delivery logs.
• Backend webhook update, secret rotation, and delivery-history endpoints.
• Persistent network selector for Testnet, Futurenet, Mainnet, and Sandbox.
• Wallet/network mismatch banner.
• Runtime network-aware Soroban configuration.
• Cashflow projection calculations, chart, horizons, runway/cliff markers, and tests.
• Batch claim drawer with selection, aggregation, and batch_withdraw client integration.

Validation: static diagnostics and git diff --check pass. Full build/tests could not run because frontend dependencies are not installed and installation was skipped. Some delivery fields such as response body and latency still require persistence fields in the backend schema.

Made changes.