feat(web): switch to the Alpine CSP build; drop 'unsafe-eval' from CSP

Standard Alpine evaluates every attribute expression through
new Function(), which a strict Content-Security-Policy cannot allow.
Swap to the official CSP-safe build (@alpinejs/csp), whose parser
evaluates expressions against registered component scope without
eval. script-src now carries only 'self' and 'unsafe-inline' (the
latter still required by the pre-paint theme flash guard).

Bindings rewritten out of the unsupported expression shapes:
- 21 multi-statement sequences across admin, audio_reader, docs,
  header, index, and reader became single component methods
  (init/loadWatchStatus hooks, commitScrub, pickSkip, pickSpeed,
  pickDefaultSpeed, chooseSleepOption, chooseSleepClockMode,
  toggleFxInvert, openPageThumbs, submitNote, clearSearch,
  pickReadingTheme)
- the header sidebar's inline x-data (openPanel/themeMode IIFE)
  became a registered sidebarShell component; openPanel itself moved
  to the header root so every sidebar panel shares one open state
- the appearance-panel  moved into the component init()
- header init() now also seeds openPanel from localStorage (or the
  admin section on /admin pages)

Alpine magics (, , , ) remain available —
the CSP evaluator injects them into scope.

The Playwright suite covers the converted surfaces end to end.

templates/docs.templ

@@ -23,7 +23,7 @@ templ DocsLayout(nav Navigation, doc Document, user User, currentPath string) {
 			<link href="/static/style.css" rel="stylesheet"/>
 			<link rel="icon" type="image/svg+xml" href="/static/favicon.svg"/>
 		</head>
-		<body x-data="docs" x-init="scrollSidebarToActive(); initializeSearch(); initializeCodeCopyButtons()" class={ "theme-" + user.Theme + " page-docs font-sans antialiased" }>
+		<body x-data="docs" class={ "theme-" + user.Theme + " page-docs font-sans antialiased" }>
 			@DocsTopbar(user)
 			<!-- Mobile drawer backdrop -->
 			<div id="docs-overlay" class="hidden fixed inset-0 z-40 lg:hidden" style="background: var(--surface-overlay);" onclick="document.getElementById('docs-sidebar').classList.add('-translate-x-full'); this.classList.add('hidden')"></div>