W-432: drop component-group modifiers from the emoji corpus

[wr]

What

Bare Fitzpatrick skin-tone swatches (🏻–🏿, e.g. :medium_skin_tone:) and hair modifiers (🦰🦱🦳🦲) surfaced as standalone search hits. They're emojibase group 2 ("component") — combining modifiers, useless inserted alone. The browser already skips this group, so they only leaked through live search.

Fix

Filter the component group out of the loaded corpus in EmojiDatabase.load, so it's absent from search and exact-match — matching the browser. SkinTone applies modifiers via hardcoded scalars, not the DB, so skin-tone application is unaffected.

Notes

• Removes the 4 hair components from search too (same rationale); easy to narrow to skin-tones-only if we want hair kept.
• Supersedes W-432: drop component-group modifiers from the emoji corpus #147 (auto-closed when its stacked base branch was deleted on the W-431 merge).

Test plan

• New componentModifiersAreExcluded test: no group-2 entries in the corpus; 🏽 gone from byHexcode and from a :medium search.
• Full suite green; verified in the dev app.

Refs W-432

[linear-code]

W-432

[wr-claude-reviewer]

Clean filter with a solid matching test — logic is correct and the three-angle test coverage (corpus invariant, byHexcode lookup, search hit) is thorough.

CI: one check (ssot) is in progress (the review pipeline itself); no failed checks.

Nit: The test comment // The reported case: the bare medium skin-tone swatch (🏽) is gone. references the bug-report context ("reported case"), which couples the comment to fix history that rots over time. Per project conventions, comments should describe the invariant, not the fix — e.g. // e.g. the medium skin-tone swatch (🏽) should not appear as a standalone hit says the same thing without the task coupling.