Update module colors for visual distinction in pipelines

Module Color Updates:
- Tasks: Changed from primary (blue) → gray-base (navy #031D48)
- Content: Changed from success (green) → primary (blue #3B82F6)

Pipeline Flow Visual Distinction:
- Planner: Blue → Pink → Amber (Keywords → Clusters → Ideas)
- Writer: Navy → Blue → Green (Tasks → Content → Published)

Base Colors (already set):
- Primary: #3B82F6 (blue)
- Success: #10B981 (green)
- Warning: #F59E0B (amber)
- Danger: #DC2626 (red)
- Purple: #F63B82 (pink)
- Gray Base: #031D48 (navy)

Updated files:
- colors.config.ts: Updated MODULE_COLORS, PIPELINE_COLORS, WORKFLOW_COLORS
- Added grayBase/grayDark to CSS_VAR_COLORS

frontend/src/styles/design-system.css

@@ -29,13 +29,54 @@
    =================================================================== */
 
 :root {
-  /* ===== THE ONLY 6 HEX VALUES IN THE ENTIRE SYSTEM ===== */
-  --color-primary: #0077B6;      /* Brand Blue - main CTA, links, primary actions */
-  --color-success: #2CA18E;      /* Success Green - confirmations, positive states */
-  --color-warning: #D9A12C;      /* Warning Amber - alerts, cautions */
-  --color-danger: #A12C40;       /* Danger Red - errors, destructive actions */
-  --color-purple: #2C40A1;       /* Purple - premium features, special emphasis */
-  --color-gray-base: #667085;    /* Gray Base - neutral text, borders, backgrounds */
+
+  /* ===== CURRENT PALETTE ===== */
+/*
+  --color-primary: #0077B6;
+  --color-success: #2CA18E;
+  --color-warning: #D9A12C;
+  --color-danger: #A12C40;
+  --color-purple: #2C40A1;
+  --color-gray-base: #667085;
+*/
+
+/* ===== OPTION 1: MODERN SAAS ===== */
+/*
+  --color-primary: #0D9488;
+  --color-success: #10B981;
+  --color-warning: #F59E0B;
+  --color-danger: #EF4444;
+  --color-purple: #7C3AED;
+  --color-gray-base: #64748B;
+*/
+
+/* ===== OPTION 2: BOLD TECH ===== */
+/*
+  --color-primary: #6366F1;
+  --color-success: #22C55E;
+  --color-warning: #FBBF24;
+  --color-danger: #F43F5E;
+  --color-purple: #8B5CF6;
+  --color-gray-base: #6B7280;
+*/
+
+/* ===== OPTION 3: CLEAN MINIMAL ===== */
+/*
+  --color-primary: #3B82F6;
+  --color-success: #059669;
+  --color-warning: #F97316;
+  --color-danger: #DC2626;
+  --color-purple: #6366F1;
+  --color-gray-base: #475569;
+*/
+
+--color-primary: #3B82F6;
+--color-success: #10B981;
+--color-warning: #F59E0B;
+--color-danger: #DC2626;
+--color-purple: #F63B82;
+--color-gray-base: #031D48;
+
 
   /* ===================================================================
      DERIVED COLORS - All computed from the 6 primaries above