style: sidebar UX polish — unified dividers, letter-spacing, contrast, font floor

- Unify sidebar dividers: one dashed style + --sidebar-rule token (replaces 4 old tokens)
- Remove total-line border from invoice/value/summary groups (keep monthly only)
- Add --text-spacing-money: 0.05em token (was hardcoded 0.02em) for price readability
- Bump 6 font sizes from 8-10px to 0.6875rem (11px minimum floor)
- Darken --muted: Dark #9e9588→#b0a99f (6.6:1), Light #6a6157→#554e46 (6.5:1)
- Remove opacity on 9 text elements that were double-muting with --muted color
- Normalize divider weight across themes: Dark/Light 75%, Glass 0.16

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

SVS-MSP-Calculator-responsive.css

@@ -156,7 +156,7 @@
     .vs-brand-name { font-size: 0.9375rem; }
     .vs-table td { padding: var(--space-sm) 3px; font-size: 0.78125rem; }
     .vs-save-row td { padding: var(--space-stack-tight) var(--space-md); }
-    .vs-footnote { font-size: 0.65625rem; line-height: 1.55; }
+    .vs-footnote { font-size: 0.65625rem; line-height: 1.7; }
 
     /* Pitch footer */
     .pitch-wrap { padding: 0; }