feat(mobile): mobile-first product (DECO-2128)

[rafavalls]

What is this contribution about?

Makes the shell and Agents page mobile-responsive using a CSS-first Tailwind approach (base classes = mobile, md: = desktop). Merges layout-update which moves the chat toggle into the page topbar and adds a sidebar collapse icon. A single isMobile JS branch in ShellLayoutInner swaps the resizable side-panel chat for a bottom sheet on mobile. All other changes are additive Tailwind classes — desktop is visually and behaviorally unchanged.

Screenshots/Demonstration

To be added — test at 390px (mobile) and 1440px (desktop) to verify.

How to Test

1. Run bun run dev and open the app
2. Resize browser to < 768px (or use DevTools mobile emulation at 390px)
3. Verify: hamburger trigger appears in the page header and opens the sidebar as a left sheet
4. Verify: chat icon in the topbar opens a bottom sheet covering nearly the full screen
5. Navigate to /agents — cards should be single-column on mobile, multi-column on desktop
6. Resize to 1440px — confirm desktop layout is completely unchanged

Migration Notes

No database migrations or configuration changes required.

Review Checklist

• PR title is clear and descriptive
• Changes are tested and working
• Documentation is updated (if needed)
• No breaking changes

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Summary by cubic

Make the shell and Agents page mobile‑first with a new bottom‑sheet chat on mobile, keeping desktop unchanged. Implements DECO-2128 with a CSS‑first Tailwind approach and a single isMobile branch in ShellLayout.

• New Features

  • Mobile chat opens as a bottom sheet reusing ChatPanel and existing chat state; a Chat toggle is now in the page header (hidden on the project home). Use Page.Header’s hideChat to remove it.
  • Mobile sidebar trigger (hamburger) added to the page header; sidebar collapse/expand controls moved into the sidebar header.
  • Agents page: single‑column cards and tighter padding on mobile; desktop grid and spacing unchanged.

• Bug Fixes

  • PageHeader: removed min-w-max and added min-w-0 on the left slot to prevent horizontal scroll on narrow screens.
  • Sheet component supports hideCloseButton to avoid duplicate close icons in the chat bottom sheet.

^{Written for commit b631b0c. Summary will update on new commits.}

[github-actions]

Release Options

Should a new version be published when this PR is merged?

React with an emoji to vote on the release type:

Reaction	Type	Next Version
👍	Prerelease	2.129.1-alpha.1
🎉	Patch	2.129.1
❤️	Minor	2.130.0
🚀	Major	3.0.0

Current version: 2.129.0

Deployment

• Deploy to production (triggers ArgoCD sync after Docker image is published)

[github-actions]

🧪 Benchmark

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