Enforce Vue, JSDoc, and modern TS rules as Errors

[silvester-pari]

In v2.1 (see #10), we introduced eslint-plugin-vue, eslint-plugin-jsdoc, and updated TS-ESLint rules, but configured them as "warn" to prevent breaking existing CI pipelines.

For v3.0, we need to enforce these standards across the company.

Acceptance Criteria:

• Remove the rule overrides in index.js that downgrade Vue, JSDoc, and TS rules to warnings.
• Set critical JSDoc type-checking rules to "error".
• Set Vue 3 recommended rules to "error".
• Provide a migration script or guide for downstream projects to autofix or manually resolve these new errors.