refactor: remove AI integration and project section/form (Pivot Implementation)

[trivedikavya]

Issue Description:
Context: Following the decision to pivot away from the AI integration feature due to increased complexity and low user adoption, we need to clean up the codebase. This includes removing the AI-driven components, the associated project management section, and the submission form.

Tasks:

• Remove AI Services: Delete/deprecate src/services/geminiService.ts, src/services/readmeAIService.ts, and src/services/webSearchService.ts.
• UI Cleanup: * Remove src/components/AIFeatureIntro.tsx, src/components/AISettingsDialog.tsx, and src/components/AssistantLauncher.tsx.
• Remove the Project Section and Project Form components (src/components/ProjectsSection.tsx, src/components/ProjectCard.tsx, and src/components/SubmitSection.tsx).
• Editor Refactoring: Remove AI-related logic from src/components/readme-editor/ReadmeEditor.tsx and associated panels.
• Config & Types Cleanup: Remove AI and Project-specific types from src/types/ and any related constants.

I Think Reducing technical debt and simplifying the core workflow of the README Design Kit to focus on high-value, manually driven design tools.