docs: troubleshooting guide for CUDA / Jetson / ROS2 / drone errors (closes #63)

[rylinjames]

Summary

Adds docs/troubleshooting.md — error signatures and fixes for the most common Reflex deployment failures. Closes #63.

Adapted from #129

@DsThakurRawat opened #129 with the same goal. The structure (CUDA/GPU → Jetson → ROS2 → Drone/MAVROS → Export → Registry → Quick diagnostics) and error signatures are theirs and accurate. Preserved via Co-Authored-By on the commit.

What's the same as #129

All the error-message captures and fix patterns — libcudnn_ops_infer.so.8 errors, cudaErrorNoKernelImageForDevice, JetPack version checks, thermal throttling guidance, MAVROS FCU connection, opset rollback, HF_HUB_DOWNLOAD_TIMEOUT, etc. These are real errors users hit and the fix recipes are right.

What changed — version + cross-ref refresh only

Refresh	Why
onnxruntime-gpu==1.18.0 → >=1.25.1	Current floor per v0.9.2 CHANGELOG (Blackwell sm_120 support)
cuDNN floor: 9.0 → 9.5	Matches nvidia-cudnn-cu12>=9.5 from v0.9.2
Driver floor: R525 → R555	The v0.9.4 doctor guard pins this — cuDNN 9.5+ requires R555+
Added Blackwell sm_120 section	RTX 5090 / B200 / GB200 trap that bit a real customer for 2 weeks (v0.9.3 doctor guard)
Added "First step: run reflex doctor" with the four v0.9.4 guards	Multi-GPU mixed arch, Jetson R35 silent fallback, cuDNN/driver skew, TRT EP empirical session test — all surface most of these errors before they manifest
Updated drone state-vector section	#129 said "PR #121 adds auto-detection." #121 was superseded by #133 which introduces explicit --state-msg-type {joint_state|imu|odom}. Section now teaches the real flag.
Cross-ref understanding_verification.md → verification.md	Renamed in #136
Cross-ref adding_a_robot.md link	Now exists (from #135)
Filename TROUBLESHOOTING.md → troubleshooting.md	Sibling convention (eval.md, embodiment_schema.md, verification.md, cli_reference.md, adding_a_robot.md — all lowercase)

Closes / supersedes

• Closes [Docs] Compile TROUBLESHOOTING.md with Common CUDA Errors #63 (the original good first issue)
• Supersedes docs: compile TROUBLESHOOTING.md with CUDA and drone errors (closes #63) #129 (closing with credit note)

Test plan

• Every version pin (onnxruntime-gpu>=1.25.1, cuDNN ≥ 9.5, driver R555+) matches what reflex doctor actually validates in source (CHANGELOG v0.9.2, v0.9.3, v0.9.4 entries)
• Every cross-referenced doc exists on main: doctor_check_list.md (✓), cli_reference.md (✓ from docs: comprehensive CLI command reference (closes #65) #134), verification.md (✓ from docs: VERIFICATION.md trust-receipt guide (closes #35) #136), adding_a_robot.md (✓ from docs: Adding-a-Robot embodiment cookbook (closes #64) #135)
• ROS2 state-vector section references the shipped --state-msg-type flag from fix(ros2): pluggable state extractors (joint_state / imu / odom) #133 (not the obsolete fix(ros2): support IMU state vector for drone embodiments #121 auto-detection)
• Quadcopter embodiment example uses the real 5-DOF action layout from the preset (3 body rates + thrust + payload trigger)
• Live preview (no docs site build wired in this repo — GitHub-rendered Markdown)