Use the real hack.build logo and fix the showcase grid

- Replace the hand-drawn wrench with the actual hack.build mark: isolate the
  pink wrench from the brand PNG onto transparent (public/hackbuild-mark.png)
  and use it for the talk tile and the Resources card.
- Showcase grid: 7 columns so the seven projects fill one row, and draw the
  hairlines from per-tile borders instead of a grey container showing through
  gaps — no more grey empty cells on an incomplete row.
- Drop the now-unused HackBuildIcon.

app/(resources)/resources/page.tsx

@@ -8,7 +8,6 @@ import {
   CubeIcon,
   KeyIcon,
   GridIcon,
-  HackBuildIcon,
 } from '@/components/resources/icons'
 import { AtlasLogo } from '@/components/resources/atlas-logo'
 
@@ -124,7 +123,7 @@ export default function ResourcesLandingPage() {
                 title="Hacking Your Hackerspace"
                 description="A talk on the patterns, pitfalls, and governance lessons behind keeping a hackerspace alive — the research from these projects, condensed into one interactive session."
                 type="Talk · Interactive"
-                visual={<HackBuildIcon />}
+                visual={<img src="/hackbuild-mark.png" alt="" />}
               />
             </div>
           </section>