feat: migrate CLI runtime to pnpm (POC)

[DevaanshKathuria]

Description

This PR implements a migration from npm to pnpm to improve CI/CD performance and dependency stability.

Key Improvements:

• Performance: Reduced fresh installation time from ~4m 13s (npm) to ~1m 19s (pnpm) — a 3.2x speedup.
• Stability: Identified and fixed several "phantom dependencies" that npm was hoisting implicitly but pnpm flagged as missing. Explicitly added:
  • tslib
  • ajv
  • ajv-formats
  • jsonfile (Fixed build error in src/apps/cli/commands/new/template.ts)
  • @stoplight/spectral-core
  • @stoplight/spectral-formatters
  • @apidevtools/json-schema-ref-parser

Verification:

• pnpm install completes successfully.
• pnpm run cli:test passes all tests locally.

Related issue(s)
Fixes #2023
Relates to #1991

[changeset-bot]

⚠️ No Changeset found

Latest commit: bac329d

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud