chore: remove trailing commas from JSON and add linter rule

[platex-rehor-bot]

Description

Remove trailing commas from all JSON files and add an ESLint rule to prevent future regressions. This is a preventive fix for the upcoming Nx 22.7.1 upgrade, which has stricter JSON parsing that fails on trailing commas.

RHCLOUD-47771

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How to test locally

1. npm install
2. npm run lint — all 16 projects should pass
3. Add a trailing comma to any JSON file (e.g. tsconfig.json) and run npm run lint again — the jsonc/comma-dangle rule should flag it as an error

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Anything reviewers should know?

• Uses eslint-plugin-jsonc (not eslint-plugin-json as originally suggested in the ticket) because:
  • The repo already uses jsonc-eslint-parser for JSON files
  • eslint-plugin-jsonc provides the specific jsonc/comma-dangle rule
  • It integrates cleanly with the existing legacy ESLint config (.eslintrc.json)
• prettier/prettier is disabled for JSON files to avoid conflicts with the jsonc rule
• Lint file patterns in project.json files expanded from package.json-only to *.json so all JSON files in each package are covered

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Checklist

• Tests: new/updated tests cover the change
• API: spec updated if endpoints changed (or N/A)
• Migrations: backwards compatible if schema changed (or N/A)
• Dependencies: no known impact to dependent services
• Security: reviewed against secure coding checklist (or N/A)

AI disclosure

Assisted by: Claude Code