homepage redesign + docs cleanup + agent prompting (#540)

* homepage redesign + docs cleanup + agent prompting improvements

- rewrote hero section: new tagline, responsive font sizing with clamp(),
  extracted shared constants for copy management
- added feature screenshots (shell isolation, github permissions, mcp tools,
  agent browser) and ensured consistent image sizing
- reworked feature section mobile layout: caption-style descriptions, bigger
  h3s, image padding
- made CTA buttons visible on all breakpoints (stacked on mobile, row on md+)
- reorganized docs/tools.mdx into single table with category dividers,
  simplified tool descriptions
- added markdown image syntax instruction to agent system prompt
- fixed InfoPopover overflow on small screens
- misc: InlineCode proportional sizing, OnboardingCard updates, shell/security
  doc improvements

Made-with: Cursor

* update pnpm-lock.yaml for agent-browser 0.25.4

Made-with: Cursor

utils/instructions.ts

@@ -281,6 +281,8 @@ Never use \`sleep\` to wait for commands to complete. Commands run synchronously
 
 When posting comments via ${pullfrogMcpName}, write as a professional team member would. Your final comments should be polished and actionable — do not include intermediate reasoning like "I'll now look at the code" or "Let me respond to the question."
 
+When embedding images (e.g. uploaded screenshots) in comments or PR bodies, always use markdown image syntax: \`![description](url)\`. Never paste a naked URL — it will not render as an image.
+
 ### Progress reporting
 
 **Task list**: at the start of every run, create an internal task list based on the steps in your current mode. Update it as you complete each step. The system automatically renders this list to the progress comment — you do not need to call \`report_progress\` for this.