build: improve tsup config for turbo

[holic]

This fixes the weirdness around running build/dev with explorer.

We have turbo configured to run build task for each dep as a prerequisite of dev task. Before this change, tsup was configured to only run DTS in a special dev mode using TSUP_SKIP_DTS (because DTS generation is slow). This meant that explorer couldn't find the DTS files it expects when building and the build would fail.

Instead, we now always build DTS when running a regular tsup build (not watch mode). When tsup is in watch mode, it skips DTS and also skips cleaning, to avoid deleting previously generated DTS files. We need this configured this way otherwise a fast task like building common package would run build + dev, where dev would clean DTS files, then explorer wouldn't be able to find them when it goes to build itself.

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[holic]

dev task uses persistent: true to mark it as a long running task (which helps warn when other tasks depend on a thing that will never complete)

thus, we need to manually specify concurrency > number of persistent tasks