fix: update thumbs up/down rating state immediately without page refresh

[iwc-byronwu]

Description

Fixes #395

Bot.tsx never passed the messageRatings / onMessageRatingChange props that BotBubble already supports, so clicking 👍/👎 saved the feedback correctly (DB + localStorage) but the icon state only updated after a page refresh.

This PR wires up the missing state:

• add a messageRatings signal in Bot.tsx
• pass messageRatings / onMessageRatingChange down to <BotBubble>

How tested

• npm run build, loaded the built dist/web.js on a local test page against a Flowise server
• Clicking 👍 now immediately turns the icon green, hides the other thumb, and opens the feedback content dialog — no refresh needed
• Rating still persists after refresh (localStorage / DB behavior unchanged)

[gemini-code-assist]

Caution

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