Add JSON output format for file report (-out=report=json)

[Apprentice2907]

In raising this pull request, I confirm the following (please check boxes):

• I have read and understood the contributors guide.
• I have checked that another pull request for this purpose does not exist.
• I have considered, and confirmed that this submission will be valuable to others.
• I accept that this submission may not be used, and the pull request closed at the will of the maintainer.
• I give this submission freely, and claim no ownership to its content.
• I have mentioned this change in the changelog.

My familiarity with the project is as follows (check one):

• I have never used CCExtractor.
• I have used CCExtractor just a couple of times.
• I absolutely love CCExtractor, but have not contributed previously.
• I am an active contributor to CCExtractor.

---

Summary

This pull request adds machine-readable JSON output for file reports using:
-out=report=json

Behavior

• Existing -out=report text output remains unchanged.
• JSON output is enabled only when explicitly requested.
• No existing CLI flags or output formats are affected.

JSON Report Content

• The JSON output mirrors the current text report and includes:
• Input source and stream mode
• Program count, program numbers, and PID details (TS)
• DVB and Teletext subtitle information
• EIA-608 and CEA-708 caption data
• Video properties (resolution, aspect ratio, frame rate)
• MPEG-4 timed text track presence and count

Implementation Notes

• Introduced a report_format option (text / json).
• Added print_file_report_json() alongside existing logic.
• Early dispatch in print_file_report() based on selected format.
• Rust CLI parser special-cases -out=report=json while preserving existing -out=report behavior.

[cfsmp3]

Closing this PR due to multiple issues:

1. Build Failures - Doesn't Compile

The Rust code references fields and types that don't exist in the codebase:

error[E0609]: no field `raw_out` on type `&args::Args`
error[E0609]: no field `report_format` on type `&mut lib_ccxr::common::Options`
error[E0433]: failed to resolve: use of undeclared type `ReportFormat`

The PR modifies parser.rs to use args.raw_out, self.report_format, and ReportFormat::Json, but none of these exist. You need to:

• Add the raw_out field to the Args struct in args.rs
• Add the report_format field to Options in lib_ccxr
• Define the ReportFormat enum

2. Mixed Concerns

The PR combines unrelated changes:

• Commit 1: "Document existing --timestamp-map option for WebVTT output" (README docs)
• Commit 2: "Add JSON output support for -out=report"

These should be separate PRs.

3. Broken Markdown

The README changes have an unclosed code block:

```bash
ccextractor input.ts --timestamp-map -o output.vtt

Missing the closing ``` fence.

4. Duplicates Existing Work

PR #2020 from x15sr71 already implements JSON output for -out=report and was deep reviewed on Jan 18. That review found 3 bugs:

• Program count wrong for multi-program streams
• has_any_captions excludes DVB/Teletext
• Video dimensions 0x0 for some files

Before submitting a new implementation, please review existing PRs for the same feature.

---

If you'd like to contribute JSON report output, please:

1. Ensure the code compiles before submitting
2. Review PR [FEATURE]: Add machine-readable JSON output for -out=report #2020 and its feedback
3. Keep PRs focused on a single feature
4. Test with various input files