hscontrol/templates: add Material for MkDocs design assets

Add design system assets for HTML templates:
- headscale.svg: Logo with optimized viewBox for proper alignment
- style.css: Material for MkDocs CSS variables and typography
- design.go: Design system constants for consistent styling

The logo viewBox is adjusted to 32.92 0 1247.08 640 to eliminate
whitespace from the original export and ensure left alignment with
text content.

hscontrol/templates/style.css

@@ -0,0 +1,145 @@
+/* CSS Variables from Material for MkDocs */
+:root {
+  --md-default-fg-color: rgba(0, 0, 0, 0.87);
+  --md-default-fg-color--light: rgba(0, 0, 0, 0.54);
+  --md-default-fg-color--lighter: rgba(0, 0, 0, 0.32);
+  --md-default-fg-color--lightest: rgba(0, 0, 0, 0.07);
+  --md-code-fg-color: #36464e;
+  --md-code-bg-color: #f5f5f5;
+  --md-primary-fg-color: #4051b5;
+  --md-accent-fg-color: #526cfe;
+  --md-typeset-a-color: var(--md-primary-fg-color);
+  --md-text-font: "Roboto", -apple-system, BlinkMacSystemFont, "Segoe UI",
+    "Helvetica Neue", Arial, sans-serif;
+  --md-code-font: "Roboto Mono", "SF Mono", Monaco, "Cascadia Code", Consolas,
+    "Courier New", monospace;
+}
+
+/* Base Typography */
+.md-typeset {
+  font-size: 0.8rem;
+  line-height: 1.6;
+  color: var(--md-default-fg-color);
+  font-family: var(--md-text-font);
+  overflow-wrap: break-word;
+  text-align: left;
+}
+
+/* Headings */
+.md-typeset h1 {
+  color: var(--md-default-fg-color--light);
+  font-size: 2em;
+  line-height: 1.3;
+  margin: 0 0 1.25em;
+  font-weight: 300;
+  letter-spacing: -0.01em;
+}
+
+.md-typeset h1:not(:first-child) {
+  margin-top: 2em;
+}
+
+.md-typeset h2 {
+  font-size: 1.5625em;
+  line-height: 1.4;
+  margin: 2.4em 0 0.64em;
+  font-weight: 300;
+  letter-spacing: -0.01em;
+  color: var(--md-default-fg-color--light);
+}
+
+.md-typeset h3 {
+  font-size: 1.25em;
+  line-height: 1.5;
+  margin: 2em 0 0.8em;
+  font-weight: 400;
+  letter-spacing: -0.01em;
+  color: var(--md-default-fg-color--light);
+}
+
+/* Paragraphs and block elements */
+.md-typeset p {
+  margin: 1em 0;
+}
+
+.md-typeset blockquote,
+.md-typeset dl,
+.md-typeset figure,
+.md-typeset ol,
+.md-typeset pre,
+.md-typeset ul {
+  margin-bottom: 1em;
+  margin-top: 1em;
+}
+
+/* Lists */
+.md-typeset ol,
+.md-typeset ul {
+  padding-left: 2em;
+}
+
+/* Links */
+.md-typeset a {
+  color: var(--md-typeset-a-color);
+  text-decoration: none;
+  word-break: break-word;
+}
+
+.md-typeset a:hover,
+.md-typeset a:focus {
+  color: var(--md-accent-fg-color);
+}
+
+/* Code (inline) */
+.md-typeset code {
+  background-color: var(--md-code-bg-color);
+  color: var(--md-code-fg-color);
+  border-radius: 0.1rem;
+  font-size: 0.85em;
+  font-family: var(--md-code-font);
+  padding: 0 0.2941176471em;
+  word-break: break-word;
+}
+
+/* Code blocks (pre) */
+.md-typeset pre {
+  display: block;
+  line-height: 1.4;
+  margin: 1em 0;
+  overflow-x: auto;
+}
+
+.md-typeset pre > code {
+  background-color: var(--md-code-bg-color);
+  color: var(--md-code-fg-color);
+  display: block;
+  padding: 0.7720588235em 1.1764705882em;
+  font-family: var(--md-code-font);
+  font-size: 0.85em;
+  line-height: 1.4;
+  overflow-wrap: break-word;
+  word-wrap: break-word;
+  white-space: pre-wrap;
+}
+
+/* Links in code */
+.md-typeset a code {
+  color: currentcolor;
+}
+
+/* Logo */
+.headscale-logo {
+  display: block;
+  width: 400px;
+  max-width: 100%;
+  height: auto;
+  margin: 0 0 3rem 0;
+  padding: 0;
+}
+
+@media (max-width: 768px) {
+  .headscale-logo {
+    width: 200px;
+    margin-left: 0;
+  }
+}