harden server, deduplicate CSS, fix layout and copy

- Parse templates once at startup instead of on every request

- Add security headers (X-Content-Type-Options, X-Frame-Options, etc.)

- Add per-request logging (IP, method, path, status, size, duration,

  referer, user-agent) — no PII in logs

- Add /healthz endpoint and graceful shutdown (SIGTERM)

- Validate waitlist emails and return proper errors on render failure

- Remove ~1700 lines of duplicate CSS appended to style.css

- Fix contribute grid (auto-fill → auto-fit for 3-card balance)

- Add accent color to contribute icons so SVGs are visible

- Center section headings, descriptions, waitlist form, and edition teaser

- Add Inter and JetBrains Mono Google Fonts

- Update hero and edition teaser copy to \"in development\"

- Add wget to Dockerfile for container healthcheck

- Point docker-compose healthcheck at /healthz

- Add .gitignore for build artifacts

Signed-off-by: Blake Ridgway <blake@blakeridgway.com>

.gitignore

@@ -0,0 +1,14 @@
+# Build artifacts
+arcline-landing
+landing
+
+# OS
+.DS_Store
+Thumbs.db
+
+# IDE
+.idea/
+.vscode/
+*.swp
+*.swo
+