refactor: Script Library and Builder design critique fixes

Library:
- Clear CTA hierarchy: "Build New Script" primary, "Import Script" ghost,
  "Manage" demoted to text link
- "New from Script" → "Import Script" (clearer label)

Script Builder:
- Add suggestion chips for first-time users (4 common MSP tasks)
- Chips auto-hide after first message

Design system normalization:
- ScriptPreviewModal: bg-black/80 → bg-black/40, text-blue-400 → text-accent-text,
  emerald save button → primary, inline rgba → CSS variables
- ScriptCodeBlock: bg-[rgba(0,0,0,0.3)] → bg-code, text-blue-400 → text-accent-text,
  text-text-muted typo fixed, emerald button → ghost style
- TemplateCard: emerald/amber/rose badges → success-dim/warning-dim/danger-dim,
  ShieldAlert amber → warning token
- ParameterDetectorStepper: blue focus ring → orange, amber → warning token,
  "Candidate" → "Variable" in stepper progress

Jargon clarification:
- "Detect Parameters" → "Find Variables"
- "Detected Parameters" → "Configurable Variables"
- "Parameters (N)" → "Variables (N)"
- Detection summary copy reworded for clarity

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

frontend/src/pages/ScriptBuilderPage.tsx

@@ -189,6 +189,7 @@ export default function ScriptBuilderPage() {
         <ScriptBuilderInput
           onSend={(content) => handleSend(content)}
           disabled={isLoading}
+          showSuggestions={messages.length === 0}
         />
       </div>