chore: normalize package repository metadata

[YfengJ]

Summary

• normalize the package repository.url from the SSH-style git@github.com:... form to git+https://github.com/apify/docusaurus-plugin-typedoc-api.git
• leave runtime code, dependencies, package versioning, and published entry points unchanged

Validation

• yarn install --immutable --mode=skip-build
• package metadata assertion for the normalized repository URL
• yarn type
• yarn build
• npm pack --dry-run --ignore-scripts --json .
• git diff --check

Note: yarn install reports existing peer dependency warnings around the current TypeScript/Typedoc range; this PR does not change dependencies.