feat(fs): accept baseDir in size (#3623)

In plugins/fs/guest-js/index.ts, the size function only sent `path`
although the Rust command accepts `options.baseDir` and the JSDoc example
passed `{ baseDir: BaseDirectory.AppData }` (a TS error, silently dropped
at runtime, so the relative path was rejected).

Adds an optional `options?: SizeOptions` parameter (new exported type).
api-iife.js regenerated. The e2e spec now measures a file and a directory
relative to AppData instead of working around the missing option.

packages/api-e2e/test/specs/fs.spec.ts

@@ -116,10 +116,11 @@ describePlugin('fs', () => {
           hasMtime: fileStat.mtime instanceof Date
         },
         lstatSize: fileLstat.size,
-        // `size` only takes absolute paths
-        size: await api.fs.size(
+        size: await api.fs.size(file, { baseDir }),
+        absoluteSize: await api.fs.size(
           await api.path.join(await api.path.appDataDir(), file)
         ),
+        dirSize: await api.fs.size(dir, { baseDir }),
         dir: { isFile: dirStat.isFile, isDirectory: dirStat.isDirectory }
       }
     }, dir)
@@ -132,6 +133,8 @@ describePlugin('fs', () => {
     })
     expect(result.lstatSize).toBe(10)
     expect(result.size).toBe(10)
+    expect(result.absoluteSize).toBe(10)
+    expect(result.dirSize).toBeGreaterThanOrEqual(10)
     expect(result.dir).toEqual({ isFile: false, isDirectory: true })
   })