fix(docs): update all npm references to pnpm

[desireddymohithreddy0925]

Summary

Resolves inconsistencies in documentation and setup scripts by enforcing pnpm install uniformly across the repository, preventing unintended package-lock.json conflicts.

Closes #2694

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 💥 Breaking change (fix or feature that changes existing functionality)
• 📝 Documentation update
• 🎨 Code style update (formatting, renaming)
• ♻️ Refactoring (no functional changes)
• 🧪 Testing
• 🏗️ Build / CI/CD / Infrastructure

Description

While the README.md was recently updated to use pnpm, several other core documentation and script files still erroneously instructed users to run npm install. This often led to lockfile conflicts and failed deployments for new contributors.

Changes made:

• DEVELOPMENT.md: Replaced all mentions of npm install and npm run with pnpm install and pnpm run.
• CONTRIBUTING.md: Standardized all package manager commands to pnpm.
• render.yaml: Updated the build command from npm install && npm run build to pnpm install && pnpm run build.
• scripts/check-deps.js: Updated the printed fix message to guide developers to run pnpm install and commit pnpm-lock.yaml rather than the package-lock.json.

Note: package-lock.json is already successfully added to .gitignore from a previous PR.

[github-actions]

GSSoC Label Checklist 🏷️

@Priyanshu-byte-coder — 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

[Priyanshu-byte-coder]

The idea here is in scope and worth having — DevTrack does want consistent empty states, and the docs really should say pnpm rather than npm. The problem is the branch, not the intent.

This branch is stacked on your task-management work, so it carries all of that too: /api/tasks, the kanban and recurrence migrations, and the scratch_*.py working files. That's why a change described in one line shows 31–35 changed files. I've closed the task-management PRs as out of scope (DevTrack is a GitHub-activity analytics dashboard, not a project tracker), which leaves this one carrying code that isn't going to land.

To move it forward:

git checkout main && git pull
git checkout -b feat/empty-states-clean
# re-apply only the EmptyState work

A PR touching src/components/EmptyState.tsx plus the widgets that use it — and nothing else — I'd review the same day. Same for the npm→pnpm docs pass on its own branch; that one is genuinely useful and would go straight in.

Leaving this open so you can force-push a clean branch to it if you'd rather not open a new one.