[brianmk]

Edit-mode follow-ups for the retained-IR renderer while editing a sketch:

• Invalidate the origin-axis line sets when updateAxesLength() rewrites their sibling coordinates. The Coin retained-IR cache now also keys on the coordinate element, so this is belt-and-braces, but it keeps the axes correct independently of that cache and is a no-op on the GL path.
• Mark the sketch edit scene camera-dependent (identity SoZoomTranslation) so the retained replay re-records on a camera move instead of replaying axis geometry stretched for the previous view.
• Guard the geometry coin converter against geometry facades that carry no geometry.

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Part 4 of a stacked series; base is the Symmetric-constraint branch.

[brianmk]

Branch rebuilt (force-pushed) to drop the experimental line-midpoint vertex commit that was inherited from #143.

Ubuntu / Build was failing here with three PartDesign tests (TestHelix.testNegativeCone, TestTopologicalProblem chamfer/fillet: 44 != 62). I bisected it to c061658d1c (inherited from #143, now closed — see #143 for the full analysis): the internal P2PSymmetric midpoint rule perturbs the solver on underdetermined sketches, so the inherited commit is gone from this branch's history.

Nothing else on this branch changed — the diff against its base is exactly the commits listed in this PR. Verified locally on the rebuilt tree: FreeCADCmd -t 0 → Ran 3558 tests ... OK (expected failures=5), plus Sketcher_tests_run 111/111, PartDesign_tests_run 28/28, Gui_tests_run 349/349.

[brianmk]

Reopened: a force-push briefly pointed this branch at the same commit as its base branch, which made GitHub treat the PR as empty and auto-close it. The branch has been corrected (it is now rebased onto its (also rebased) base with the experimental line-midpoint commit dropped) and the diff is back to this PR's own commits.

[brianmk]

Superseded by #149 — this PR was auto-closed and could not be reopened after a force-push briefly pointed its branch at its own base branch. The content is identical, rebased onto the rebased #144 with the experimental line-midpoint commit dropped.