chore(ui-scripts): add transpile-diff tooling script

[balzss]

Summary

• Adds a transpile-diff command (packages/ui-scripts/lib/commands/transpile-diff.ts) for verifying that build-tooling changes — Babel→SWC, tsc→tsgo, preset/TypeScript bumps — don't unintentionally alter emitted code.
• For each of two git refs it builds the repo in an isolated worktree, normalizes the es//lib//types/ output (strips banner, sourcemaps, whitespace), diffs the snapshots, and writes an HTML report. Snapshots are cached by commit SHA so unchanged refs skip rebuild.
• --semantic reprints through dprint so formatting-only diffs are ignored (recommended for cross-compiler comparisons); exits non-zero on any real change. Meant for occasional local use, not CI.
• Includes contributor docs at docs/contributor-docs/transpile-diff.md.

Test Plan

• pnpm run transpile-diff runs the current branch vs master and produces an HTML report
• pnpm run transpile-diff master <branch> and pnpm run transpile-diff v9.0.0 HEAD work with branches, tags, and SHAs
• --semantic collapses formatting-only differences to zero
• Re-running against an unchanged ref skips the rebuild (cache hit)
• A build failure on a ref aborts with a clear message rather than a misleading diff

Jira Reference

INSTUI-5054

AI Disclosure

This PR was created with AI assistance (Claude Code).

🤖 Generated with Claude Code

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PR Preview Action v1.8.1
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2026-06-10 08:53 UTC

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Visual regression report

✅ No changes.

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Changed	0
New	0
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