Rename Hand output structure to Gesture

[amyjko]

Summary

• The Hand input stream returns a structure with place, open, fingers, and per-finger booleans. Naming the structure Hand too collided with the stream's name in every locale (same 🖐️ emoji and, in many locales, the same text), which the locale verifier rejects as a global-name duplicate.
• Renamed the output structure to Gesture (emoji ✋) so the stream and result type have distinct identities. Stream usage is unchanged: Hand() still works; the returned value now has type Gesture.

Changes

• src/locale/OutputTexts.ts, src/locale/en-US.json: rename output.Hand → output.Gesture (new emoji ✋).
• src/output/Hand.ts: update locale.output.Gesture references throughout createHandType, plus the shares.output.Gesture lookup in createHandStructure.
• src/runtime/createDefaultShares.ts: rename OutputTypes.Hand → OutputTypes.Gesture.
• 25 other locales updated via npm run locales-fix (removed Hand, added Gesture placeholder) and npm run locales-translate (filled in machine translations for the structure's names and field names).
• ko-KR doc cleanup: Google Translate had wrapped @Hand in backticks, which broke the structure parser. Dropped the cross-reference sentence in en-US and stripped the artifact from ko-KR.

Test plan

• `npm run check:now` — type-check passes
• `npm run locales` — locale verifier passes (no "Name '🖐️' is already used" error, no parsing errors)
• Open the Hand example and confirm the structure still renders correctly on stage
• In the editor, type `hand: Hand()` then access `hand.place`, `hand.open`, etc. — autocomplete should still work

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