fix(css): serve live theme CSS verbatim instead of diverging SCSS fork

The Sass file in sass/_praxis_theme.scss had drifted from the live
_style.css over the project's life — different line-heights (34/28 vs
24), padding overrides, restructured selectors, and a few sections that
the SCSS parser couldn't accept anyway (CSS // line-comments, missing
semicolons inherited from the original hand-written CSS).

For Phase 1 visual parity the correct source of truth is the live CSS,
not a re-edited copy. Drop compile_sass, ship the live _style.css as
/css/praxis.css straight from static/, and point base.html at it. This
restores the live vertical rhythm (paragraph spacing, banner padding)
that had been subtly off.

templates/partials/head.html

@@ -20,4 +20,4 @@
 <link rel="stylesheet" href="/fonts/font-awesome/css/font-awesome.min.css">
 <link rel="stylesheet" href="/css/mobile-menu.css">
 <link rel="stylesheet" href="/css/flexslider.css">
-<link rel="stylesheet" href="/main.css">
+<link rel="stylesheet" href="/css/praxis.css">