chore(deps): override esbuild to ^0.28.1 (CVE fix)

Adds an npm override forcing esbuild to ^0.28.1, resolving the moderate
dev-server arbitrary file read advisory (GHSA affecting esbuild < 0.28.1).
esbuild is a transitive dev dependency pulled in by vite and vitest, which
previously resolved to 0.27.7. The get-intrinsic override is preserved.

Verified: esbuild resolves to 0.28.1 across the tree, npm audit reports 0
vulnerabilities, and client lint, client tests (535), cli tests (85), and
the full build all pass.

Resolves Dependabot alert #121
Part of #1706

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HiccCEh9mwCfVzE8qYcop1

Author: cliffhall