fix: tsc errors — restore Root type import, fix exactOptionalPropertyTypes for oldProgram

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: DrSkillIssue

packages/ganko/src/css/phases/parse.ts

@@ -3,7 +3,7 @@
  *
  * Parse CSS/SCSS files from input and create FileEntities.
  */
-import postcss, { CssSyntaxError } from "postcss"
+import postcss, { CssSyntaxError, type Root } from "postcss"
 import safeParse from "postcss-safe-parser"
 import postcssScss from "postcss-scss"
 import type { CSSGraph } from "../impl"

packages/ganko/test/solid/test-utils.ts

@@ -69,12 +69,13 @@ export function createTestProgram(files: Record<string, string>): ts.Program {
     },
   }
 
-  const program = ts.createProgram({
+  const opts: ts.CreateProgramOptions = {
     rootNames: [...fileMap.keys()],
     options: compilerOptions,
     host,
-    oldProgram: lastProgram ?? undefined,
-  })
+  }
+  if (lastProgram) opts.oldProgram = lastProgram
+  const program = ts.createProgram(opts)
   lastProgram = program
   return program
 }