List third-party bar widgets that declare display modes in the Icons editor

[monsonjeremy]

Summary

Third-party bar widgets can opt into the Control Center's Icons appearance editor by declaring the displayMode values they render:

"x-shibumi": { "displayModes": ["full", "icon", "text"] }

Today the editor builds its list from the fixed WidgetCatalog groups, so a third-party widget that already honors the displayMode setting the host injects (icon / full / text) has no tile and no way for the user to pick a mode (omarchy bar set … displayMode is overwritten by the group store). With this change:

• ControlCenterPanel.buildPluginEntries carries a validated displayModes list per plugin (unknown values dropped; a widget that cannot render full is not listed).
• WidgetAppearanceWorkbench adds one catalog option per enabled, declared, non-suite bar widget under its dynamic G:<plugin id> group, and the mode chooser offers only the declared modes in V2. V1 keeps such widgets at Default, matching normalizedDisplayMode in the state service. Surface/color/outline controls apply through the host slot as before.
• Widgets without the declaration keep their original rendering and stay in Plugins, so existing behavior is unchanged.

Affected plugins: hancore.shibumi.control-center (plus docs, changelog, and tests). No state-service or bar-host changes.

Motivating widget: monsonjeremy.omachess, which declares the key and renders all three modes.

Checks

git diff --check
python3 tests/documentation-regression.py
SHIBUMI_OMARCHY_BASELINE_PROFILE=installed-source-parity \
  OMARCHY_PATH=<basecamp/omarchy checkout at f0020448> \
  ./tests/control-center-regression.sh

All pass. The smoke test now adds a flag-gated third-party fixture entry (thirdPartyAppearanceFixture on the test panel, so baseline widget counts asserted elsewhere are untouched) and asserts that a declared widget is listed with modes icon,full in V2 and Default-only in V1, and that an undeclared widget is not listed. I confirmed the new assertion fails against main without the implementation.

tests/test_shibumi_suite.py was run but its test_sandbox_update_advances_beta_7_to_beta_9 errors on my shallow clone (missing tag v0.1.1-beta.7); the other 98 tests pass and the error reproduces on an unmodified tree.

The installed-package baseline could not be used because my installed Omarchy shell drifts from the pinned package digest, hence the source-parity profile.

Live evidence and remaining gate

Widget side, on a real Wayland session (Omarchy shell + Shibumi 0.1.1-beta.11, V2 layout): writing displayMode icon / text / full into bar.shibumi.widgets["G:monsonjeremy.omachess"] renders the expected pill in each mode, which is the path this editor writes through setGroupSetting.

Not exercised live: the modified Control Center itself on a Wayland session (I did not want to overlay files onto a suite-managed install). The remaining gate is opening Icons with a declared third-party widget enabled and confirming the tile, preview glyph, mode chooser, and reset behave in both V1 and V2.