feat(mcap): switch single-source exports to copy layout

Namespace single-source zed_svo_to_mcap outputs with a derived camera label so one-camera exports use the same copy-layout topic shape as current multi-camera copy files.

Use the per-camera frame and pose reference identifiers for those single-source outputs, document copy as the current one-camera wire shape, and clarify that legacy /camera/* files are retained only as a legacy contract.

Add a small mcap_rgbd_example helper plus mcap_recipes guide for summarizing bundled/copy MCAPs and exporting one RGB/depth sample, and update the validator and viewer wording/behavior to match the bundled-vs-copy semantics.

scripts/mcap_bundle_validator.py

@@ -339,7 +339,7 @@ def print_summary(summary: McapSummary) -> None:
 @click.argument("paths", nargs=-1, type=click.Path(path_type=Path))
 @click.option("--recursive", is_flag=True, help="Recursively discover *.mcap files under directory inputs.")
 def main(paths: tuple[Path, ...], recursive: bool) -> None:
-    """Summarize and validate single-camera or bundled MCAP files."""
+    """Summarize and validate legacy single-camera, bundled, or copy-layout MCAP files."""
     if not paths:
         raise click.ClickException("provide at least one MCAP file or directory")