Add support for SRT (SubRip Subtitle) file format

[vrcprl]

What

Implement a loader for SRT files in Replexica.

Why

To support video editors and translators working with video subtitles.

How

1. Create a new loader in packages/cli/src/loaders/srt.ts
2. Implement parsing logic for SRT structure
3. Add two unit tests in packages/cli/src/loaders/index.spec.ts:
   • Test parsing a simple SRT file
   • Test handling multi-line subtitles in SRT entries
4. Update @replexica/spec to include SRT format
5. Generate a changeset using pnpm new for both 'replexica' and '@replexica/cli' packages
6. In the pull request, include a link to the SRT specification used.

After completing the task

Noticed a file format Replexica doesn't yet support? Please create a new GitHub ticket (if it doesn't yet exist!), using the format/structure of this GitHub issue.

[partik03]

@maxprilutskiy please assign this issue to me I am already trying to solve this

[maxprilutskiy]

@partik03 assigned, go for it!