fix(trajectory): honour non-zero time origins in scalar profiles

[YaoxinHuang]

Summary

quintic and trapezoidal document scaling by the first and last times, but treat the last timestamp as the duration. For quintic(0, 1, np.linspace(5, 7, 5)), the first position is about 0.855 instead of 0; valid trapezoidal velocities can also be rejected.

Use elapsed time for scalar profiles while retaining the supplied timestamps. Apply the same time origin to trapezoidal plot phases and show the supplied time range on each subplot. Keep ctraj sampling its existing zero-origin profile directly so unordered samples retain their behaviour. Add regressions for positive/negative origins, endpoint velocities, multi-axis trajectories, plot ranges and phase samples.

Validation on Windows/Python 3.12:

• Required CPU suite: 762 passed, 70 skipped, 17 subtests passed, using UTF-8 mode and a writable pytest temporary directory.
• Ruff formatting and git diff --check pass. Ruff lint has the same 14 existing diagnostics as the base revision.
• Native extensions came from the matching 1.4.4 Windows wheel and were not rebuilt locally; optional collision/Swift tests remain skipped.

Prepared with Codex; the validation above was run locally.

Related issue

None.

Checklist

• PR title follows Conventional Commits (type: description)
• Tests pass locally (pytest)
• Added/updated tests for this change, if applicable
• New/changed code is type-hinted with modern syntax
• Docstrings updated (reST style)
• PR is as small/focused as practical
• No test files, data files, or notebooks specific to your own project

[petercorke]

Thanks for finding this. I think the same issue will exist for jtraj().

[codecov]

Codecov Report

❌ Patch coverage is 0% with 20 lines in your changes missing coverage. Please review.
✅ Project coverage is 0.00%. Comparing base (477b6e3) to head (a6e3932).

Files with missing lines	Patch %	Lines
src/roboticstoolbox/tools/trajectory.py	0.00%	20 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #698   +/-   ##
=====================================
  Coverage   0.00%   0.00%           
=====================================
  Files        143     143           
  Lines      14093   14097    +4     
=====================================
- Misses     14093   14097    +4     

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[petercorke]

Thanks supporting the Robotics Toolbox. Your PR is now merged. As per the previous comment, the issue might apply to jtraj as well.