Pass Eagle/Fusion board variant as metadata instead of in the title

[DominikPalo]

Follow-up to #574.

Since #574 the BOM header shows the board variant from pcbdata.metadata.variant (see populateMetadata in web/ibom.js), and the %v / %V output name format substitutions in core/ibom.py read the same key. The KiCad parser sets it, but the Eagle/Fusion parser never did. It appended the current variant to the title instead:

title = "{0}, Variant: {1}".format(title, variant)

So for Eagle/Fusion boards with a current <variantdef>:

• the new variant cell in the header stayed hidden,
• the title was long and got truncated in the header ("withvariant.brd, Variant…"),
• %V in --name-format always produced default, and %v was empty.

This change stores the current variant in metadata['variant'] and leaves the title as the file name. When no variant is current, the variant key is omitted rather than set to an empty string: Eagle/Fusion variant names are required and the default assembly variant is implicit, so there is never an empty-named variant (details in the comment below).

Testing

Eagle test boards generated with --name-format "%f_%V":

	master	this PR
Board with <variantdef name="LITE" current="yes"/>: metadata.title	withvariant.brd, Variant: LITE	withvariant.brd
metadata.variant	missing	LITE
Header variant cell	hidden	"Variant: LITE"
Output file name	withvariant_default.html	withvariant_LITE.html
Board with empty <variantdefs/>	no variant cell, novariant_default.html	unchanged, variant key omitted
Board with variants defined but none current (default variant active)	no variant cell, nocurrent_default.html	unchanged, variant key omitted

Checked the generated pages in a browser: the header renders correctly and there are no console errors.

Note for reviewers

The page's local storage key prefix is derived from the title. For Eagle/Fusion boards with an active variant the title changes, so checkbox state saved in BOMs generated before this change won't be picked up by BOMs generated after it.

🤖 Generated with Claude Code

[qu1ck]

Does eagle/fusion always specify a variant even if user didn't customize anything? If there is a distinction between variant that is empty string and no variant I'd like to keep it reflected in the data, even if it shows up on the page the same at the moment.

[DominikPalo]

No, Eagle/Fusion don't always specify a variant, and a variant never has an empty name. Per the DTD, variantdef requires a name. The default assembly variant is implicit and is never stored. Real boards on GitHub I checked either have an empty <variantdefs/> or a named variant marked current="yes".

So the only distinction is a named variant vs no variant. I've updated the PR (772b2ae) to omit metadata.variant when no variant is current instead of setting it to "".