fix(build): select the core Zig project explicitly

Review threads live on the whole diff, not on one commit, so none are shown here - a thread's line means something in the branch's final form, and painting it into an intermediate step would put it on code it is not about.

scripts/verify-zig-core-project.tsmodified+2-1

Changes to scripts/verify-zig-core-project.ts

		@@ -1,10 +1,11 @@
1		-import { mkdtempSync, mkdirSync, readFileSync, rmSync, writeFileSync } from 'node:fs'
	1	+import { existsSync, mkdtempSync, mkdirSync, readFileSync, rmSync, writeFileSync } from 'node:fs'
2	2	import { tmpdir } from 'node:os'
3	3	import { join, resolve } from 'node:path'
4	4	import { resolveZig } from './zig'
5	5
6	6	const source = resolve(import.meta.dir, '..')
7	7	const zig = resolveZig(source)
	8	+console.log('Tracked core project:', JSON.stringify({ file: join(source, 'packages/zig/build.zig'), exists: existsSync(join(source, 'packages/zig/build.zig')) }))
8	9	const root = mkdtempSync(join(tmpdir(), 'craft-core-project-'))
9	10	const core = join(root, 'packages', 'zig')
10	11	try {