utils: add RobotDescriptionCache for URDF download and mesh embedding

[abhichothani42]

Summary

This PR adds a small utility that resolves a robot name to its URDF, downloading and caching files locally, and optionally embeds all meshes as base64 data URIs so the resulting URDF is fully self-contained and portable.

Changes

• Add RobotDescriptionCache::resolve(robot_name, urdf_variant, git_ref, include_meshes) — returns the URDF string for a robot, downloading from TrossenRobotics/trossen_arm_description at the given git ref on cache miss.
• Files are cached under ~/.cache/trossen_sdk/robot_description/<git_ref>/ so repeated recordings never re-download.
• With include_meshes=false, package:// mesh references are rewritten to absolute local cache paths (usable by Rerun on the same machine). With include_meshes=true, meshes are embedded as base64 data URIs (usable anywhere, including Foxglove).
• Link libcurl into trossen_sdk and add libcurl4-openssl-dev to the CI dependencies.

Test Plan

• Builds cleanly (make build)
• Tests pass(make test)
• Lint passes (pre-commit run --all-files)
• Tested on hardware

Breaking Changes

None. New utility, not called by anything yet.

Related Issues

None.

[abhichothani42]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• scripts: add Foxglove user scripts for robot and EEF visualization #277
• scripts: add URDF extraction tool for TrossenMCAP recordings #276
• examples: enable robot description recording in solo demo #275
• backend: write robot description to TrossenMCAP files #274
• config: add robot description options to TrossenMCAP backend #273
• utils: add RobotDescriptionCache for URDF download and mesh embedding #272 👈 (View in Graphite)
• examples: update sanity check for end-effector pose #270
• arm: emit end-effector pose from TrossenArmProducer #269
• backend: add end-effector pose write support to TrossenMCAP #268
• arm: add EndEffectorPoseRecord and proto schema #267
• examples: add trossen_vr_mobile demo #266
• examples: add trossen_vr_stationary demo #265
• examples: add trossen_vr_solo demo #264
• vr: add VrSessionControlComponent button-to-session bridge #263
• vr: add VrBaseComponent base-velocity teleop leader #262
• vr: add VrArmComponent cartesian teleop leader #261
• vr: add shared VrSession connection owner #260
• feat: post_event/attach_control queue for thread-safe session control #271
• session-control: add SessionControlCapable interface #259
• hw: make SlateBaseComponent a base-velocity teleop follower #258
• teleop: add base-velocity (Base) space to teleop interface #257
• main

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[Copilot]

Pull request overview

This PR introduces a new RobotDescriptionCache utility in trossen_sdk to resolve a configured robot name (or explicit URDF path) into a URDF string by downloading from TrossenRobotics/trossen_arm_description, caching artifacts locally, and optionally embedding meshes/textures as base64 data URIs for portability.

Changes:

• Add RobotDescriptionCache::resolve(...) implementation + public header.
• Add libcurl as a required dependency and link it into trossen_sdk.
• Update CI system dependencies to install libcurl4-openssl-dev.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 7 comments.

File	Description
src/utils/robot_description_cache.cpp	Implements download, cache, and URDF path rewriting / mesh embedding logic.
include/trossen_sdk/utils/robot_description_cache.hpp	Declares the public API and documents behavior/config parameters.
CMakeLists.txt	Adds the new source file and links CURL::libcurl into trossen_sdk.
.github/workflows/build.yml	Installs libcurl4-openssl-dev in CI to satisfy the new dependency.

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