Improve Developer Experience and Documentation

**Goal**: Enhance developer onboarding and daily workflow through improved docs and editor settings.

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### Tasks
- Write a comprehensive DEVELOPMENT.md (setup, structure, troubleshooting)
- Add VSCode workspace settings (`.vscode/settings.json` and `.vscode/extensions.json`)
- Document PocketBase schema in `docs/SCHEMA.md`
- Add troubleshooting guide `docs/TROUBLESHOOTING.md`
- Upgrade main README with badges, quick start, diagram, guidelines, demo credentials

**References:** See [QUICK_WINS.md](https://github.com/adhit-r/aran/blob/main/QUICK_WINS.md)

**Acceptance Criteria**
- New contributors can onboard and run the project with docs alone
- Recommended extensions/settings enforced for VSCode
- Schema and troubleshooting docs committed
- README clearly covers setup, usage, contribution, and project highlights

Start by reading QUICK_WINS.md, the existing README, and the repository's current documentation and editor configuration. Update or add DEVELOPMENT.md, .vscode/settings.json, .vscode/extensions.json, docs/SCHEMA.md, and docs/TROUBLESHOOTING.md, then verify the README and onboarding flow satisfy the listed acceptance criteria.

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