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-light.css

@@ -8,7 +8,7 @@
   --ink: #2c2825;
   --paper: #e2dccf;
   --accent: #637f88;
-  --muted: #6a6157;
+  --muted: #554e46;
   --border: #c3baab;
   --border-soft: #cdc6ba;
   --card: #ece4d6;
@@ -119,8 +119,7 @@
   --sidebar-zone-value: rgba(33, 112, 69, 0.04);
   --sidebar-zone-summary: rgba(0, 0, 0, 0.02);
   --sidebar-row-stripe: rgba(0, 0, 0, 0.02);
-  --sidebar-line-rule: color-mix(in srgb, var(--border) 70%, transparent);
-  --sidebar-total-rule: color-mix(in srgb, var(--border) 90%, transparent);
+  --sidebar-rule: color-mix(in srgb, var(--border) 75%, transparent);
   --surface-switch-off: #b5ad9f;
   --surface-switch-on: var(--green);
 }