feat(site): 🫙 PCBJam landing revisions — branding, accuracy, positioning graphic

Founder review pass on the landing page, plus commit the landing-page
research/spec docs under features/lp.

Branding & assets:
- New PCBJam mark: convert the jam-jar image to favicon.svg (trimmed, rounded
  tile) and use it in the browser tab, header, and footer.
- Footer "Built by": flower mark + "Emergence Engineering" in white Oswald (the
  blog's title font, self-hosted via @fontsource) so it's legible on dark.
- Produce the positioning quadrant graphic (public/graphics) and drop the placeholder.

Copy / accuracy:
- Remove header GitHub link; point "Built by EE" + footer "About" to
  emergence-engineering.com; Built-by CTA -> mailto:contact@emergence-engineering.com.
- Replace the wrong testimonial with Greg Detre's real quote from EE's site.
- Drop blog icons from Multiplayer/Pillars/How-it-works; add "Coming soon" to
  live-cursors & pin-comment; drop the hard-coded Yjs mention.
- Rework monetization to free+local / paid cloud-sync; remove "no metered AI",
  "no per-seat toll", and the Flux price claim; soften the AI section.
- Reframe waitlist copy (incl. confirmation email) to newsletter + early access.

Fixes:
- Offset only #waitlist for the sticky header (scroll-margin-top); section
  anchors keep their original behavior.

Docs:
- Commit features/lp (copy spec, brand guide, competitive research) via force-add
  over the /features/ gitignore.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

site/package-lock.json

@@ -9,6 +9,7 @@
       "version": "0.0.1",
       "dependencies": {
         "@astrojs/vercel": "^10.0.8",
+        "@fontsource/oswald": "^5.2.8",
         "astro": "^6.4.4",
         "resend": "^6.12.4"
       },
@@ -638,6 +639,15 @@
         "node": ">=18"
       }
     },
+    "node_modules/@fontsource/oswald": {
+      "version": "5.2.8",
+      "resolved": "https://registry.npmjs.org/@fontsource/oswald/-/oswald-5.2.8.tgz",
+      "integrity": "sha512-DFoPK1BqsFIQhVjs2xgO/oL9veF9oUJgFojEWIU+nazUrfqsBDtAMI4n9L9CZFX3kQNDLcCyzKx1xoEDvQT4WQ==",
+      "license": "OFL-1.1",
+      "funding": {
+        "url": "https://github.com/sponsors/ayuhito"
+      }
+    },
     "node_modules/@img/colour": {
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/@img/colour/-/colour-1.1.0.tgz",