style(design): migrate to DESIGN.md system

Full visual migration: Space Grotesk + DM Sans + JetBrains Mono fonts,
warm amber two-accent system (amber=state, blue=action), dark mode with
CSS vars + localStorage + FOUC prevention, mobile bottom nav (5 tabs),
full-width tables, error/skipped dot glow, ~13 hardcoded hex replaced
with CSS vars in 4 JS files, 5 new E2E tests.

Files: style.css (full rewrite), base.html (fonts, theme script, dark
toggle, bottom nav), settings.html (dark toggle card), dashboard.js,
logs.js, mappings.js, settings.js (color vars), 5 templates (bnav
active blocks), test_design_system_e2e.py (NEW).

Cache-bust: style.css?v=18, shared.js?v=14, dashboard.js?v=27,
logs.js?v=13, mappings.js?v=12, settings.js?v=8

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/tests/e2e/test_order_detail.py

@@ -51,5 +51,5 @@ def test_dashboard_navigates_to_logs(page: Page, app_url: str):
     page.goto(f"{app_url}/")
     page.wait_for_load_state("networkidle")
 
-    logs_link = page.locator("a[href='/logs']")
-    expect(logs_link).to_be_visible()
+    logs_link = page.locator(".top-navbar a[href='/logs'], .bottom-nav a[href='/logs']")
+    expect(logs_link.first).to_be_visible()