Fix component detail modal: replace dead hx-* with fetch-based JS

HTMX was never loaded on the page, so hx-get on the component label
spans was dead code — the dialog opened empty. Replace with a plain
openComponentDetail() fetch call. Also fix dialog positioning broken
by the CSS reset (*{margin:0} overrode the UA margin:auto that centers
<dialog>). Replace card hx-trigger polling with a setInterval.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

audit/internal/webui/layout.go

@@ -17,6 +17,7 @@ func layoutHead(title string) string {
 <style>
 :root{--bg:#fff;--surface:#fff;--surface-2:#f9fafb;--border:rgba(34,36,38,.15);--border-lite:rgba(34,36,38,.1);--ink:rgba(0,0,0,.87);--muted:rgba(0,0,0,.6);--accent:#2185d0;--accent-dark:#1678c2;--crit-bg:#fff6f6;--crit-fg:#9f3a38;--crit-border:#e0b4b4;--ok-bg:#fcfff5;--ok-fg:#2c662d;--warn-bg:#fffaf3;--warn-fg:#573a08}
 *{box-sizing:border-box;margin:0;padding:0}
+dialog{margin:auto}
 body{font:14px/1.5 Lato,"Helvetica Neue",Arial,Helvetica,sans-serif;background:var(--bg);color:var(--ink);display:flex;min-height:100vh}
 a{color:var(--accent);text-decoration:none}
 /* Sidebar */