onlook feat: Handle network disconnection errors better

Description

Adds graceful network-loss handling to the web client.
NetworkStore (MobX) – constantly pings an external endpoint, classifies latency, performs exponential back-off, exposes
helpers (manualRetry, checkConnection, events).
use-chat hook – snapshots partial assistant messages, pauses streaming when the connection drops, and automatically resumes (or lets the user retry) when the connection is back.
NetworkWarning banner – surfaces live connection status with animated icons and “Try Again” / “Retry Chat” buttons.

Related Issues

closes #2226 - Handle network disconnection errors better

Type of Change

[ ] Bug fix
[x] New feature
[ ] Documentation update
[ ] Release
[ ] Refactor
[ ] Other (please describe):

Testing

Disabled network (Airplane-mode or DevTools “Offline”).
Send a chat prompt – banner appears, stream pauses, retry buttons enabled then Auto-resumed.
Re-enabled network – banner disappeared, stream continues from the exact point where it stopped.
Max retries - Stay offline past the max back-off interval – banner switches to red state, “Try Again” and “Retry Chat” buttons work. 5.Regression checks - Normal online chat flow unaffected. Lint & type-check show same warnings as main.

Screenshots (if applicable)

Watch demo video on Loom

Heads-up: the video was recorded before the latest UI polish (icon swap + color tweaks on the warning banner).
Functionality is identical—only the visual styling changed in my most recent commits.

Additional Notes

Scope limited to apps/web/client; backend & shared packages untouched. No DB migrations, env-var, or API changes

[!IMPORTANT] Enhances network disconnection handling in the web client with a new NetworkStore, updated chat management, and a NetworkWarning component.

Behavior:

Adds NetworkStore class in network/index.ts for monitoring network status, handling reconnections, and emitting network events.

Updates use-chat.tsx to manage chat state during network disconnections, including pausing and resuming chat streams.

Introduces NetworkWarning component in network-warning.tsx to display connection status and retry options to users.

Components:

ChatMessages component updated to include NetworkWarning for displaying network status.

NetworkWarning component shows different messages and actions based on network status (offline, reconnecting, max attempts reached).

Utilities:

Adds utility functions in network/utils.ts for pinging server, calculating connection quality, and debouncing functions.

Misc:

Adds network-related types in network/types.ts.

Integrates NetworkStore into EditorEngine in engine.ts.

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