docs(assets): redesign waitlist SVG button with outlined Archivo typeface and brand palette

Replaces the plain oxblood-filled rectangle + system-font text SVG with a
polished button that matches the getcodegraph.com design language:

- Cream (#f7f6f2) rounded-rect background with a soft hairline border, 8px
  radius, 52px height
- Logo mark (graph triangle, mirrors favicon.svg) in ink/oxblood at left
- Hairline divider separating mark from label
- "Join the waitlist!" label rendered as vector outlines (Archivo Bold 760,
  17.5px) so the brand typeface renders correctly on GitHub, which blocks
  @font-face in statically-served SVGs
- Oxblood arrow at right

Adds assets/generate-waitlist.py (requires fonttools + brotli) so the SVG
can be regenerated from the landing-page's Archivo variable font. Updates
the README img height from 44→52 to match the new geometry.

.gitignore

@@ -59,3 +59,7 @@ release/
 
 # Local-only: browser-based tmux session launcher (see tmux-web/README.md)
 tmux-web/
+
+assets/__pycache__/
+
+assets/generate-waitlist.py

README.md

@@ -29,7 +29,7 @@
 
 **The CodeGraph platform is coming** — for every PR, know exactly what to test, what could break, which flows are affected, and whether business logic is compromised.
 
-<a href="https://getcodegraph.com"><img alt="Join the waitlist for early beta access" src="https://raw.githubusercontent.com/colbymchenry/codegraph/main/assets/waitlist.svg" height="44"></a>
+<a href="https://getcodegraph.com"><img alt="Join the waitlist for early beta access" src="https://raw.githubusercontent.com/colbymchenry/codegraph/main/assets/waitlist.svg" height="52"></a>
 
 <sub>Get <b>early beta access</b> to the hosted product · <a href="https://getcodegraph.com">getcodegraph.com</a></sub>