perf(build): cut npm run build RAM, time, and output size

[SudoThijn]

Ports the build-performance fixes from openregister PR #108 to opencatalogi.

Results

Clean production build (npm run build), peak RAM sampled across the whole webpack process tree:

Metric	Before	After	Improvement
Build time	61.6 s	13.6 s	4.5× faster
Peak RAM	9.56 GB	3.16 GB	3.0× less
js/ output size	162 MB	23 MB	86% smaller

What changed

webpack.config.js

• esbuild minifier in place of Terser (TerserPlugin.esbuildMinify, parallel: false, legalComments: 'eof'). esbuild parallelises internally, so webpack-worker parallelism is disabled to avoid redundant Node processes.
• No production source maps. The config was forcing devtool = 'inline-source-map' unconditionally (a later override that beat the isDev ? … : … line), embedding base64 source maps into every bundle. Now false in production — this accounts for most of the size drop.
• cache = false in production — the in-memory cache is unused in a single-shot build and only added heap pressure.
• splitChunks vendor cacheGroup. node_modules was being bundled into all 5 entrypoints (each 54–92 MB). It now lands once in a shared opencatalogi-vendor.js (18 MB), shrinking the per-entry chunks to KBs.
• Entrypoints manifest emitter — writes js/opencatalogi-entrypoints.json mapping each entry to its ordered initial chunks (vendor → shared → entry).

PHP (required so the shared vendor chunk loads before each entry)

• New lib/Service/ScriptManifestLoader.php reads the manifest and enqueues each chunk via Util::addScript, falling back to the legacy single-script name when the manifest is absent.
• Updated the 5 script-loading callsites to use it: templates/index.php, templates/settings/admin.php, and the three lib/Dashboard/*Widget.php files.
• New tests/Unit/Service/ScriptManifestLoaderTest.php covering every manifest fallback branch (missing file, unknown entry, invalid JSON, non-array JSON, happy path).

package.json — adds esbuild and terser-webpack-plugin to devDependencies.

Drive-by fix

The committed config could not build locally at all: the @nextcloud/dialogs alias lacked a $, making it a prefix alias that hijacked @nextcloud/dialogs/style.css → a raw path bypassing the package's exports map. Made it exact (@nextcloud/dialogs$), matching the other singleton aliases (vue$, pinia$, @nextcloud/vue$). The baseline numbers above were taken with this fix applied, so the comparison is apples-to-apples.

Verification

• npm run build succeeds; manifest and opencatalogi-vendor.js emitted as expected.
• phpcs, phpstan, psalm clean on all changed PHP files.
• phpunit — ScriptManifestLoaderTest 5/5 passing.

Notes for reviewers

• No runtime behaviour change for users: the loader emits the same scripts, just split and ordered, with a graceful fallback.
• js/ build output (including the manifest) is gitignored and produced fresh by CI.
• Remaining build warnings are benign: standard webpack "entrypoint size exceeds 244 KiB" hints (present before too) and one Duplicate key "euro" notice esbuild surfaces from a third-party dependency that Terser silently ignored.