fix(web): make chat app icons theme-aware

[bobleer]

Summary

• Render Telegram, Feishu, and WeChat marks with the current theme foreground color.
• Remove decorative backgrounds and borders in Remote Connect, the device overview, and the navigation footer.
• Add contract coverage for the monochrome, unframed presentation.

Type and Areas

Type: UI/UX regression fix

Areas: web UI, Remote Connect, device overview

Motivation / Impact

Chat-app marks previously used success or accent coloring and were placed inside tinted framed containers. They now remain recognizable monochrome marks while following the active theme, with connection state communicated by the existing status UI.

Verification

• pnpm --dir src/web-ui run test:run src/app/components/RemoteConnectDialog/RemoteConnectDialog.contract.test.ts — 26 tests passed
• pnpm run check:web — passed; only pre-existing Appearance owner warnings were reported
• git diff --check — passed

Testing level: fully tested with the focused and repository-prescribed automated Web UI checks. A live Telegram, Feishu, or WeChat bot connection was not exercised.

Reviewer Notes

This change is AI-assisted. It targets 1.0.0-explore because these Remote Connect components are not present on main. The change is presentation-only: no remote protocol, connection lifecycle, locale, persisted shape, or platform adapter behavior changes.

Remote scenarios: the local Remote Control UI path was covered by contract and build-time checks. Remote workspace, Peer Device Mode, and Detached Dispatch behavior are unchanged and were not exercised end to end.

Checklist

• This PR is focused and does not include secrets, temporary prompts, generated scratch files, or unrelated artifacts.
• Relevant verification is recorded above, or skipped checks are explained.
• User-facing strings, docs, and locales are unchanged and not applicable.