New /diy hub: curated resources for making your own gear, with cross-links into
the rest of the app.
- src/lib/diyGuides.ts: seed data — categories (Boards, Ramps & wooden
obstacles, Concrete & DIY spots, Repairs & tuning, Tools & plans), resource
cards (Open Source Skateboards / SK8CAD / Instructables / YouTube), and an
actions block (find a Builder, find a DIY crew, map a DIY spot, sell builds,
find a coach).
- src/pages/DiyPage.tsx renders it (category chips + card grid + actions);
external links go through sanitizeUrl and credit the source.
- Route /diy (lazyWithRetry) + a nav-catalog entry (id diy) so it appears in the
desktop "More" menu and the mobile burger; also linked from the site footer
and the map links strip. Smoke test walks /diy.
