fix(docs): map exact source aliases in built checks

scripts/doc-typecheck-paths.spec.ts

@@ -0,0 +1,17 @@
+import { describe, expect, it } from 'vitest'
+import { builtDeclarationPath } from './doc-typecheck-paths.ts'
+
+describe('builtDeclarationPath', () => {
+  it('maps package source directories and exact entry files to built declarations', () => {
+    expect(builtDeclarationPath('./packages/*/*/src')).toBe('./packages/*/*/lib/types')
+    expect(builtDeclarationPath('./packages/support/invariants/src/index.ts'))
+      .toBe('./packages/support/invariants/lib/types/index.d.ts')
+    expect(builtDeclarationPath('./packages/core/session/src/invariant.ts'))
+      .toBe('./packages/core/session/lib/types/invariant.d.ts')
+  })
+
+  it('rejects aliases without a supported source target', () => {
+    expect(() => builtDeclarationPath('./packages/support/invariants/source/index.ts'))
+      .toThrow('cannot map workspace source path')
+  })
+})