Refactor admin pages to use shared head and navigation components

- Created `admin-head.php` for consistent <head> markup across admin pages.
- Created `admin-nav.php` for shared navigation bar, reducing duplication.
- Updated all admin pages (account, hours, index, login, menu, users) to utilize the new components.
- Added security headers to `auth.php` and `index.php` for improved security.
- Introduced `security-headers.php` to manage security headers across the application.
- Moved inline styles from admin pages to SCSS files to comply with Content Security Policy (CSP).
- Normalized file permissions during build process to prevent permission issues on deployment.

src/scss/pages/_admin-announcements.scss

@@ -0,0 +1,29 @@
+/* ---------- admin: announcements ---------- */
+/* Formerly inline style="" attributes on admin/index.php — moved here so
+   the CSP can forbid inline styles. */
+.ann-summary {
+	font-size: 0.82rem;
+	margin-top: 0.2rem;
+	max-width: 32ch;
+	white-space: nowrap;
+	overflow: hidden;
+	text-overflow: ellipsis;
+}
+
+.ann-schedule {
+	font-size: 0.8rem;
+	color: var(--ink-muted);
+}
+
+.ann-placements {
+	font-size: 0.82rem;
+	color: var(--ink-muted);
+}
+
+.ann-field-hint {
+	font-size: 0.78rem;
+}
+
+.inline-form {
+	display: inline;
+}

src/scss/pages/_admin-hours.scss

@@ -141,3 +141,12 @@
     grid-template-columns: 1fr;
   }
 }
+
+/* Formerly inline style="" attributes on admin/hours.php. */
+.hours-note {
+  margin-top: 1.25rem;
+}
+
+.hours-preview-intro {
+  margin-bottom: 1.25rem;
+}

src/scss/pages/_menu.scss

@@ -94,5 +94,61 @@
 }
 
 .menu-page-content {
+  padding-top: 0;
   padding-bottom: 5.5rem;
 }
+
+/* Formerly inline style="" attributes on menu.php — moved here so the
+   CSP can forbid inline styles. */
+.menu-hero {
+  text-align: center;
+}
+
+.menu-hero-title {
+  font-size: clamp(2.4rem, 5vw, 3.8rem);
+  color: var(--gold-bright);
+  margin-top: 0.5rem;
+}
+
+.menu-hero-rule {
+  margin-top: 1.5rem;
+  margin-bottom: 1.5rem;
+}
+
+.menu-hero-intro {
+  max-width: 52ch;
+  margin: 0 auto;
+  font-size: 1.05rem;
+}
+
+.menu-page-container {
+  max-width: 62rem;
+}
+
+.menu-grid-flush {
+  margin-top: 0;
+}
+
+.menu-empty {
+  text-align: center;
+  padding: 3rem 1.5rem;
+}
+
+.menu-disclaimer {
+  margin-top: 3.5rem;
+  text-align: center;
+  padding-top: 2rem;
+  border-top: 1px solid var(--rule);
+}
+
+.menu-disclaimer-text {
+  font-size: 0.8rem;
+  line-height: 1.6;
+  max-width: 68ch;
+  margin: 0 auto;
+}
+
+.menu-disclaimer-ctas {
+  margin-top: 2rem;
+  justify-content: center;
+}

src/scss/styles.scss

@@ -31,4 +31,5 @@
 @use "pages/admin-login";
 @use "pages/admin-menu";
 @use "pages/admin-hours";
+@use "pages/admin-announcements";
 @use "pages/admin-account";