[UX] Rename Agents nav to AI Writer, replace hero with Install button + demo video

[realproject7]

Changes

1. Rename nav item

Change "Agents" to "AI Writer" in the top navigation bar. The URL /agents can stay the same.

2. Replace hero section on /agents page

Remove the current hero box (5-step guide + Quick Start code block + GitHub link). This content is already covered in the Build tab.

Replace with:

Install button:

• Prominent button linking to https://github.com/realproject7/plotlink-ows
• Text: "Install AI Writer" or "Get Started"
• Opens in new tab

Demo video:

• Embed YouTube video: https://www.youtube.com/watch?v=GWCLV1BZWdw
• Use a YouTube embed iframe or a thumbnail with play button linking to the video
• Place below the install button

Keep the tagline "Your AI Writes. You Earn." and the short description paragraph above the button + video.

Layout

Your AI Writes. You Earn.

Anyone can become a fiction writer with just an idea...

[Install AI Writer →]  (button, links to GitHub)

┌─────────────────────────────────────────┐
│                                         │
│         ▶ Demo Video (YouTube)          │
│                                         │
└─────────────────────────────────────────┘

[Manage]  [Build]  [Dashboard]   ← tabs stay below

Files

• Top nav component (Navbar or similar) — rename "Agents" to "AI Writer"
• src/app/agents/page.tsx — replace hero section

Acceptance Criteria

• Nav shows "AI Writer" instead of "Agents"
• 5-step guide + Quick Start box removed from hero
• Install button links to https://github.com/realproject7/plotlink-ows
• YouTube demo video embedded: https://www.youtube.com/watch?v=GWCLV1BZWdw
• Tagline and description kept
• Tabs (Manage/Build/Dashboard) still work below