feat: add CameraLabelsComponent for typed per-camera image labels

[janickm]

Summary

Add a new V4 CameraLabelsComponent for storing per-camera image-aligned labels (depth maps, optical flow, segmentation masks, surface normals, etc.) with typed, schema-validated storage.

• Tagged-union type system: LabelCategory enum (DEPTH, FLOW, SEGMENTATION, MASK, GEOMETRY, MATERIAL, FEATURE, OTHER) + free-form qualifier string. New label variants require zero code changes.
• Dual encoding: RAW array storage (Blosc lz4) and IMAGE_ENCODED (PNG, JPEG) with handle-based deferred decoding for GPU pipelines.
• Independent timestamps: Each label instance has its own timestamps, decoupled from camera frame rate.
• Ergonomic compat API: CameraLabelsProtocol, CameraLabel sub-protocol, query_camera_labels(camera_id, label_type?, label_category?).

Commits

1. CameraLabelsComponent with tagged-union type system, compat layer, and tests — Core implementation: LabelCategory, LabelType(category, qualifier, unit), CameraLabelDescriptor, LabelSchema, CameraLabelsComponent (Writer/Reader), CameraLabelsProtocol, CameraLabel protocol, SequenceLoaderV4 integration, ComponentGroupAssignments extension, 12 round-trip tests.

2. Migrate Waymo panoptic segmentation from generic_data to CameraLabelsComponent — First real-world usage: Waymo converter now stores panoptic_label_png as SEGMENTATION/"panoptic" with IMAGE_ENCODED/png encoding. Per-label metadata carries the panoptic_label_divisor. Class-ID map moved from camera sensor metadata to label component metadata.

3. Add camera label overlay support to ncore_vis — CameraComponent gains a "Camera Labels" overlay option with label source dropdown, opacity slider, and replace-image toggle. Category-aware rendering: depth (TURBO colormap), segmentation (20-color palette), masks (green tint), geometry/normals (RGB mapping), generic (grayscale).

Design

See Camera Labels Component Design wiki page for full design spec including dataverse, sauron, and NRE compatibility tables.

Files Changed

Area	Files
Type system	ncore/impl/data/types.py
Component	ncore/impl/data/v4/components.py
Compat layer	ncore/impl/data/compat.py, ncore/impl/data/v4/compat.py
Group assignments	ncore/impl/data/v4/types.py
Public API	ncore/data/__init__.py, ncore/data/v4/__init__.py
Tests	ncore/impl/data/v4/components_test.py
Waymo converter	tools/data_converter/waymo/converter.py
Visualization	tools/ncore_vis/components/camera.py, tools/ncore_vis/data_loader.py
Other converters	tools/data_converter/{colmap,pai}/converter.py (added camera_labels_ids=[])