[UI] Add empty state for Projects section on Home Screen

[Codewithpabitra]

Description

Currently, when a user opens DataLoom for the first time (or has no projects),
the Projects section only shows the "+ New Project" card against a large blank
white space. There is no visual guidance or call-to-action to help new users
understand what to do next.

Current Behavior

• The home screen shows only the + New Project card
• The rest of the page is empty white space
• No guidance is provided to first-time users

Expected Behavior

• When recentProjects is empty, display a friendly empty state below the grid
• The empty state should include:
  • A subtle illustrated icon (table/grid)
  • A short message: "No projects yet"
  • A hint pointing users to the New Project card

Screenshots

Why This Matters

This is a common UX pattern that improves the onboarding experience for
first-time users. It makes the interface feel complete and intentional rather
than broken or unfinished — especially important for a tool aimed at
non-technical users.

Proposed Solution

Add a conditional empty state component in HomeScreen.jsx that renders
when recentProjects.length === 0. No new dependencies required —
uses existing Tailwind CSS classes and inline SVG.

Additional Context

• File to modify: src/components/HomeScreen.jsx
• No backend changes required
• No new dependencies required