v0.22.0 — Moderated success-stories wall (/stories)

A public, no-login user-stories wall — students/professionals share how
CatchIt helped them catch a hackathon spot, credits, a scholarship, etc.

• /stories: submission form (zod validation, honeypot, IP rate-limit,
  same anti-spam pattern as /submit) plus a Padlet-style card wall.
• Moderated by default: every story lands pending; only visible after
  an admin approves it in /admin — same trust model as the opportunities
  review queue (anon can only insert, admins read/moderate via RLS, public
  reads through a narrow stories_public view).
• Empty-wall guard: the wall only renders once there are 3+ approved
  stories, so a near-empty page never ships.
• Footer and About page now link to /stories instead of a mailto.

Migration: 20260710000000_stories.sql.