fix(diagram): keep trivial molecules visible while something is flagged

[adamjohnwright]

Curators, testing on beta: "H2O and H+ disappear with zooming out." And separately #150: a molecule's chemical structure drawn with no molecule underneath it. Those are the same fault seen from two sides — the node was hidden while a different handler carried on drawing its structure.

Why the previous fix did not hold

Flagging pins trivial molecules visible by marking them .always-visible — deliberately a class rather than an inline style, so nothing could lose it.

But the zoom handler writes an inline opacity across every .trivial element, and in cytoscape an inline style beats any stylesheet rule. It painted straight over the class. Detaching it from the zoom event — what the previous attempt did — was not enough, because triggerZoom() calls it directly: on every restyle (a theme change, an analysis loading) and whenever an interactor is opened.

The class is now the authority. The handler leaves anything wearing it alone.

Measured on beta, flag active:

	before	after
as the diagram loads	opacity 0	1
zoomed out	0	1
zoomed in	0	1
after a restyle	0	1

With no flag, molecules still fade out as you zoom away and come back as you zoom in — unchanged.

Why it took two attempts to land

build:libs did not build reactome-cytoscape-style. CI compensated with a step of its own, so a fix to that library passed CI and never reached the dev server, which builds the app without building the library. I spent a while concluding the fix did not work when it had simply never been compiled.

build:libs now covers every workspace library and build depends on it, so any path that produces the app produces what it links against. CI's two special-case steps are gone: it runs the same command a developer runs.

The test

End-to-end rather than a unit test, for two reasons: the library cannot be constructed headlessly (its layers plugin refuses outright), and the bug lives in what a real renderer computes rather than in a pure function.

It reads opacity through the registration cytoscape keeps on its own container, which beats sampling canvas pixels — those cannot tell you which element was faded.

Verified to fail without the fix: both flagging tests go red, the unflagged one stays green.

Fixes #150
Fixes #143