feat: bring rvctool up to date with rtbtool/mvtbtool, add --test smoke test

[petercorke]

Summary

Catches rvctool up to feature parity with its siblings (rtbtool/mvtbtool), and adds the smoke-test capability requested for it specifically:

• New --test flag + run_smoke_test(): prints real package versions, then one real functional check per toolbox (RTB fkine, MVTB Image.smooth, spatialgeometry Cuboid, spatialmath SE3 composition, Open3D PointCloud, and bdsim -- running vloop_test.py's block diagram non-interactively). Missing optional deps (Open3D) are reported as FAIL with reason, not silently skipped. Mirrors mvtbtool's own --test design.
• New tests/test_bin.py, mirroring MVTB's tests/test_bin.py pattern: subprocess-invokes rvctool --help/--test, asserts exit codes and expected PASS/FAIL output.
• New RVC3/bin/_bintools.py: line-wrapping argparse help formatter, RVC3's own copy of the same private helper RTB/MVTB each keep in their own bin/ package.
• New RVCTOOL_OPTIONS env var (RVCTOOL kept for backward compat, now prints a deprecation warning when used).
• New --torch and --reload flags, matching mvtbtool/rtbtool.
• Version banner rewritten: wrapped multi-line (was a single unwrapped line), now includes bdsim and Open3D ("not installed" if missing) alongside RTB/MVTB/SG/SMTB/NumPy/SciPy/Matplotlib. Fixes a bug where SG's line reported spatialmath-python's version twice instead of spatialgeometry's own.
• IPython/pygments/traitlets imports guarded with a friendly install message instead of a hard top-level import failure.
• Fixed the %precision startup line spuriously auto-displaying its own return value (bare Out[]: '%.3g;' printed before the first real prompt) -- same class of bug also just fixed upstream in rtbtool (fix: rtbtool's %precision line spuriously echoes its own return value robotics-toolbox-python#592) and mvtbtool (fix: mvtbtool's %precision line spuriously echoes with --showassign machinevision-toolbox-python#79).
• Suppressed IPython's own generic startup banner (Python/IPython version, tips) since rvctool already prints its own richer one.
• Fixed a real bug surfaced live while testing: exec("from spatialgeometry import *", globs) injects SG's exported names directly into the module's own globals(), including a class also named Path -- silently shadowing pathlib.Path for the rest of the function. Switched all internal path handling to explicit pathlib.Path so it can't be shadowed by a wildcard import.
• mvb import alias fixed to match what the banner actually advertises (was bound as mvbase in code but mvb in the printed banner text).
• README: documented rvctool --test as a post-install sanity check, and updated the example transcript to match (removed IPython's now-suppressed native banner lines).

Test plan

• rvctool --help -- exits 0, well-formatted
• rvctool --test -- reports PASS/FAIL per toolbox, exits 1 when Open3D genuinely missing
• rvctool (default interactive startup) -- confirmed clean banner, no double-banner, no spurious echo, verified live
• python -m unittest tests.test_bin -- 2 passed