fix: remove invalid source package exports

[HamedFarazi]

Summary

Removes invalid source conditional exports from packages that exclude
their exports/** source files from the published npm package.

Affected packages:

• react-aria
• react-stately
• react-aria-components
• @adobe/react-spectrum

When a bundler is configured with the source condition, these exports
can resolve to ./exports/*.ts files that are not included in the
published package. Removing the invalid condition allows resolution to
fall back to the distributed import entry.

Changes

• Remove the source export from the root export.
• Remove the source export from the wildcard export.
• No other package configuration or build files were changed.

🤖 AI Assistance

This PR was prepared with AI assistance. The changes were reviewed by me, and I understand the purpose and impact of
each change.

✅ Pull Request Checklist:

• Included link to corresponding React Spectrum GitHub Issue.
• Added/updated unit tests and storybook for this change (not applicable: this is a package export configuration fix).
• Filled out test instructions below.
• Updated documentation (not applicable).
• Looked at the Accessibility Practices for this feature (not applicable: this is a package resolution fix).
• I understand every change in this PR and can explain why it's there.
• If AI-assisted, I followed our AI contribution guidance and pointed my assistant at https://github.com/adobe/react-spectrum/blob/main/CLAUDE.md.

📝 Test Instructions:

Validation performed locally:

• git diff --check — passed.
• JSON parsing validation for all four modified package.json files — passed.

The repository's runtime/type-checking tests were not run because the
local node_modules state was not installed, so yarn check-types and
yarn test:ssr could not be executed.

Expected behavior:

1. Install the repository dependencies.
2. Run yarn check-types.
3. Run yarn test:ssr.
4. Run the relevant test suite for package resolution.
5. Verify that packages configured with the source condition resolve
   to their distributed import entry instead of the missing
   exports/**/*.ts files.

🧢 Your Project:

Personal open-source contribution.