Feat/character customization 2387

[Bhavy12-cell]

Summary

Closes #2387

Problem

There was no way for users to personalize stories before generation.
The dashboard had no character input form, so all stories used
generic default characters with no user involvement.

Solution

Added a full character customization flow before story generation:

• Users can define Hero Name, Villain Name, Setting, and Mood
• All fields are optional with smart fallback defaults
• Values are dynamically injected into the AI prompt
• Generated story is displayed below the form

New Files

• src/components/CharacterForm.tsx
  Input form UI with 4 fields: Hero Name, Villain Name, Setting, Mood.
  Exports CharacterConfig interface used across components.

• src/lib/promptBuilder.ts
  Pure utility function that injects character values into the AI
  prompt string. Falls back to defaults if any field is left empty.

• src/components/StoryGenerator.tsx
  Wraps CharacterForm, calls the AI API with the built prompt,
  and renders the generated story below the form.

Modified Files

• src/app/dashboard/page.tsx
  Added StoryGenerator component just before the Career
  Intelligence banner so users see it naturally in the flow.

How It Works

1. User opens the dashboard
2. Sees the Character Customization form
3. Fills in Hero Name, Villain Name, Setting, Mood (all optional)
4. Clicks "Generate Story"
5. promptBuilder.ts builds the prompt with their values
6. Story is generated and displayed instantly below the form

Acceptance Criteria

• ✅ Character input form on UI
• ✅ Inputs injected into AI prompt via promptBuilder
• ✅ Generated story reflects custom characters
• ✅ Default fallback values used when fields are left empty
• ✅ No breaking changes to existing dashboard widgets

[github-actions]

GSSoC Label Checklist 🏷️

@Umbrella-io — please apply the appropriate labels before merging:

Difficulty (pick one):

• level:beginner — 20 pts
• level:intermediate — 35 pts
• level:advanced — 55 pts
• level:critical — 80 pts

Quality (optional):

• quality:clean — ×1.2 multiplier
• quality:exceptional — ×1.5 multiplier

Validation (required to score):

• gssoc:approved — counts for points
• gssoc:invalid / gssoc:spam / gssoc:ai-slop — does not score

Type labels (type:*) are auto-detected from files and title. Review and adjust if needed.
Points formula: (difficulty × quality_multiplier) + type_bonus