feat: migrate build from Rollup + SWC to esbuild

[kpal81xd]

Summary

• Migrates the PlayCanvas engine JS build pipeline from Rollup + SWC to esbuild
• Replaces sequential Rollup builds with parallel esbuild builds (Promise.all)
• Replaces @rollup/plugin-strip + @rollup/plugin-swc with unplugin-strip for function call stripping
• Adds custom esbuild plugins for shader chunks, JSCC preprocessing, dynamic imports, and import validation
• TypeScript definitions still built via Rollup (rollup-plugin-dts) — unchanged
• Removes unused Rollup plugins (rollup-dynamic, rollup-import-validation, rollup-shader-chunks, rollup-spaces-to-tabs, rollup-swc-options)

Build Comparison Report

Benchmarked on the same machine, 3 runs each, median reported.

Build Times

Builder	Median	Runs
esbuild	15.4s	15458ms, 15380ms, 15709ms
Rollup + SWC	40.6s	40657ms, 43917ms, 37274ms
Speedup	2.63x

Bundled File Sizes

File                   |    esbuild |     Rollup |    Δ% |     esb gz |    roll gz | Δ gz%
-----------------------+------------+------------+-------+------------+------------+------
playcanvas.js          |       3.5M |       3.4M |  1.6% |     716.7K |     690.1K |  3.8%
playcanvas.mjs         |       3.5M |       3.3M |  5.2% |     716.6K |     683.5K |  4.8%
playcanvas.dbg.js      |      17.1M |      20.7M |-17.1% |       3.7M |       4.7M |-21.3%
playcanvas.dbg.mjs     |      17.1M |      20.0M |-14.3% |       3.7M |       3.9M | -6.4%
playcanvas.prf.js      |       3.5M |       3.4M |  1.6% |     718.0K |     691.4K |  3.8%
playcanvas.prf.mjs     |       3.5M |       3.3M |  5.2% |     717.9K |     684.8K |  4.8%
playcanvas.min.js      |       2.1M |       2.0M |  1.5% |     552.6K |     533.3K |  3.6%
playcanvas.min.mjs     |       2.1M |       2.0M |  1.1% |     552.5K |     536.0K |  3.0%
playcanvas.d.ts        |       2.0M |       2.0M |    0% |     402.6K |     402.6K |    0%

Unbundled Directories

Directory              |  esb # | roll # |   esb size |  roll size |    Δ%
-----------------------+--------+--------+------------+------------+------
playcanvas/            |   2240 |   2254 |       7.5M |       6.5M | 14.0%
playcanvas.dbg/        |   1133 |   1130 |       6.4M |       6.3M |  1.7%
playcanvas.prf/        |   1110 |   1124 |       4.5M |       3.6M | 25.4%

Correctness

• TypeScript definitions: IDENTICAL
• Export surface area: IDENTICAL (1251 exports)
• Unbundled file lists: Minor differences in code-splitting (14–32 files differ per directory)

Known Differences

• UMD wrapper: esbuild uses self fallback; Rollup uses globalThis
• Export block: esbuild emits individual export statements; Rollup emits a single export {} block
• Debug builds are ~14–17% smaller with esbuild (no SWC runtime helpers)
• Release/min builds are ~1–5% larger with esbuild (different tree-shaking heuristics)

Test plan

• Run node build.mjs — all 12 JS targets + types build successfully
• Run node build.mjs target:esm:release:bundled — single target works
• Verify build/playcanvas.d.ts is identical to main
• Verify export surface matches main (playcanvas.mjs)
• Spot-check a built example in the browser

🤖 Generated with Claude Code