Accept corrected position type counts message

[liurenfeng94-ops]

Fixes a small typo in the shared message schema.

The positionTypeCounts schema currently accepts the misspelled message name postionTypeCounts. This adds the correctly spelled positionTypeCounts name while still accepting the legacy spelling, so existing callers do not break.

Validation:

• pnpm vitest run test/position-type-counts-message.test.ts
• pnpm vitest run
• pnpm typecheck
• pnpm exec eslint .
• pnpm build

[github-actions]

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[liurenfeng94-ops]

Thanks — I checked this again and rewrote the description plainly. The new spelling is accepted, but the old misspelled message name still parses so this stays backward compatible.