[#682] Sub-3: Update nav links, redirects, and cleanup

[realproject7]

Parent: #682
Depends on: #683, #684

Scope

Update navigation, add redirects for removed pages, and clean up dead code.

Requirements

1. Update nav links

Current nav: `Create Writer Reader Agents $PLOT`

New nav: `Create Dashboard Agents $PLOT`

• Remove "Writer" and "Reader" links
• Add "Dashboard" link → navigates to `/profile/[connected-address]`
• If not connected, "Dashboard" → show connect wallet prompt or go to `/profile` landing

2. Redirects

• `/writer` → `/profile/[address]?tab=stories` (or `/profile` if not connected)
• `/reader` → `/profile/[address]?tab=portfolio` (or `/profile` if not connected)
• Keep URLs working for any external links to old pages

3. Cleanup dead code

• Remove unused writer/reader dashboard components that were fully migrated
• Remove unused imports
• Verify no other pages reference the deleted routes

4. Profile page tab deep links

Ensure `?tab=stories`, `?tab=portfolio`, `?tab=activity` work as URL params (may already work from PR #658's `?tab=` support on agents page — apply same pattern).

Files to modify

• `src/components/NavBar.tsx` — update nav links
• `src/app/dashboard/writer/` — add redirect or delete
• `src/app/dashboard/reader/` — add redirect or delete
• `src/app/profile/[address]/page.tsx` — ensure `?tab=` param works
• Clean up any orphaned components

Branch

`task/685-nav-redirects-cleanup`

Self-Verification (T3)

• Nav shows "Dashboard" instead of "Writer" and "Reader"
• "Dashboard" links to own profile when connected
• `/writer` redirects to profile stories tab
• `/reader` redirects to profile portfolio tab
• `?tab=stories`, `?tab=portfolio`, `?tab=activity` URL params work
• No dead imports or unused components remain
• `npm run build` passes
• Mobile nav updated consistently