Fix trapezoidal velocity trajectory generation time scaling

[sea-bass]

In the previous implementation, every trajectory used its own limits by only ensuring it finished at the same time. While this worked, it means that technically all the degrees of freedom were not synced up.

In this PR, we change the logic to make sure that a single time scaling is computed with the most limiting speed/acceleration in consideration, and then use that for all degrees of freedom.

This ends up simplifying the math significantly, as there is no longer a quadratic to solve!

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
pyroboplan
__init__.py	0	0	100%
pyroboplan/core
__init__.py	0	0	100%
planning_context.py	8	8	0%	1, 4, 9, 13–15, 17–18
utils.py	85	2	97%	155–156
pyroboplan/ik
__init__.py	0	0	100%
differential_ik.py	87	14	83%	146–147, 156–157, 181, 187, 193, 196, 224, 227, 235–236, 241, 247
nullspace_components.py	16	16	0%	3, 6, 22, 25, 45–46, 48–54, 57, 75–76
pyroboplan/models
__init__.py	0	0	100%
panda.py	41	0	100%
utils.py	4	0	100%
pyroboplan/planning
__init__.py	0	0	100%
cartesian_planner.py	92	5	94%	115, 139, 143–144, 207
graph.py	40	0	100%
rrt.py	158	25	84%	129–130, 132–133, 149, 152, 160, 333, 378–383, 387–388, 392–394, 397–398, 406–407, 410–411
utils.py	6	0	100%
pyroboplan/trajectory
__init__.py	0	0	100%
polynomial.py	126	18	85%	127, 129–130, 132–134, 136–137, 140–143, 146, 151, 156, 165, 192, 261
trapezoidal_velocity.py	153	18	88%	283–284, 316, 318–322, 324–325, 328–331, 334, 339, 344, 353
pyroboplan/visualization
__init__.py	0	0	100%
meshcat_utils.py	18	11	38%	40–41, 43, 45, 57, 81–82, 109–111, 113
TOTAL	834	117	85%

Tests	Skipped	Failures	Errors	Time
62	0 💤	0 ❌	0 🔥	17.262s ⏱️