Add package.json catalog support for npm completions and hover

[yogeshwaran-c]

Summary

• Extends the npm extension to recognize the catalog section in package.json, enabling IntelliSense completions, version suggestions, and hover information for packages listed under the catalog key
• Supports the catalog feature used by pnpm, bun, and yarn for centralizing dependency versions in monorepos
• Adds location.matches(['catalog']) and location.matches(['catalog', '*']) to the three relevant methods in packageJSONContribution.ts: collectPropertySuggestions, collectValueSuggestions, and getInfoContribution

Fixes #294609

Test plan

• Open a package.json file that contains a catalog section (e.g., a pnpm workspace root)
• Verify that typing a package name inside "catalog": { } triggers npm package name completions
• Verify that typing a version value for a catalog entry triggers version suggestions (latest, ^latest, ~latest)
• Verify that hovering over a package name in the catalog section shows package description, latest version, and homepage
• Verify that existing dependencies, devDependencies, optionalDependencies, and peerDependencies behavior is unchanged

[aeschli]

Are unrelated changes to AI instruction files. Please remove these.

[aeschli]

Should not be included in this PR.

[yogeshwaran-c]

Removed the unrelated AI instruction files. PR now only contains the npm catalog change (1 file, 3 lines).