feat: Sprint 0 — GoFiber + HTMX + TailwindCSS v4 scaffolding

- Go module: git.tukangketik.id/swanadiva/hostkeeper/v2
- GoFiber v2 server with static, template engine, middleware
- HTMX + Alpine.js (downloaded from CDN)
- TailwindCSS v4 with custom theme (Lumina System colors)
- Custom CSS: dot-grid, glassmorphism, animations, toggle, modal
- Layout template (sidebar nav + header + main)
- Dashboard page with host list, search, filter, view toggle
- Health endpoint: GET /api/health

app/backend/static/css/input.css

@@ -0,0 +1,33 @@
+@import "tailwindcss";
+
+@theme {
+  --color-primary: #0050cb;
+  --color-on-primary: #ffffff;
+  --color-primary-container: #d6e3ff;
+  --color-on-primary-container: #001638;
+  --color-secondary: #006e2f;
+  --color-on-secondary: #ffffff;
+  --color-secondary-container: #6bff8f;
+  --color-on-secondary-container: #00210b;
+  --color-tertiary: #7e23cc;
+  --color-on-tertiary: #ffffff;
+  --color-tertiary-container: #f0daff;
+  --color-on-tertiary-container: #290055;
+  --color-error: #b3261e;
+  --color-on-error: #ffffff;
+  --color-error-container: #f9dedc;
+  --color-on-error-container: #410e0b;
+  --color-surface: #f7f9fb;
+  --color-on-surface: #191c1e;
+  --color-surface-container-low: #f0f2f5;
+  --color-surface-container: #eaecf0;
+  --color-surface-container-high: #e2e5e9;
+  --color-on-surface-variant: #424656;
+  --color-outline: #727686;
+  --color-outline-variant: #c2c6d8;
+  --color-inverse-surface: #2d3133;
+  --color-inverse-on-surface: #f0f1f3;
+
+  --font-sans: 'Inter', ui-sans-serif, system-ui, sans-serif;
+  --font-mono: 'JetBrains Mono', ui-monospace, monospace;
+}