ci: remove partial build logic

[Mrtenz]

Explanation

The partial build logic was useful in CI when a full build took 4-5 minutes. Since the switch to TypeScript 7, a full build only takes 12 seconds, so there is no point in keeping the partial build logic.

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Low Risk
CI-only simplification with no application or security impact; full builds may add a few seconds versus partial builds but improve consistency.

Overview
CI build no longer does merge-base–aware partial TypeScript builds. The build job always runs yarn build, and the extra unshallow fetch plus generate-partial-build-tsconfig.mts / tsc --build path are gone.

The scripts/generate-partial-build-tsconfig.mts helper is deleted. Partial builds existed to save time when full builds were slow; with faster full builds (per PR description), that complexity isn’t worth keeping. Prepare still computes changed paths for ESLint and tests—only the build step is simplified.

^{Reviewed by Cursor Bugbot for commit 6c5c83c. Bugbot is set up for automated code reviews on this repo. Configure here.}

[mcmire]

Great!