feat(spm): clean scoping flags + JS-root cwd guard

Two related changes to setup-apple-spm.

* `npx react-native spm clean` gains scoping flags. Default behavior is
  unchanged (generated dirs only). Each flag widens the deletion scope:
    --project       also Package.swift + <App>-SPM.xcodeproj/
    --derived-data  also ~/Library/Developer/Xcode/DerivedData/<App>-SPM-*
    --cache         also the current resolved-nightly cache slot under
                    ~/Library/Caches/com.facebook.ReactNative/spm-artifacts/
    --all           shorthand for the three above
    --yes           skip confirmation for destructive scopes; non-TTY auto-confirms

  Refactored cleanGeneratedState() to a pure gatherCleanTargets(appRoot, opts)
  enumerator plus a thin I/O wrapper. App name for the DerivedData glob is
  discovered from any *-SPM.xcodeproj actually present in appRoot, so the
  scope can't accidentally hit DerivedData entries that don't belong to
  this app. Cache slot is resolved via the same resolveCacheSlotVersion
  used elsewhere, so the nightly-hash-keyed slot is targeted (not a stale
  '1000.0.0/' or 'nightly/' label).

* A guard refuses runs from the JS root of a standard RN app, where the
  community CLI writes autolinking.json under <projectRoot>/ios/... but
  every SPM script anchors on cwd. The result was a silently-broken build:
  the autolinker missed autolinking.json, generated an empty Autolinked
  package, the build compiled fine, and any native module crashed at
  runtime. describeRnRootMismatch returns a "cd ios && ..." message when
  cwd === projectRoot AND <projectRoot>/ios/ exists as a directory.
  Flat layouts (rn-tester) are explicitly safe — no ios/ subdir, no
  refusal — and covered by a regression test.

* 13 new unit tests in setup-apple-spm-test.js: 9 for gatherCleanTargets
  (each flag in isolation, additive composition, missing-xcodeproj edge
  case) and 4 for describeRnRootMismatch (RN layout triggers, subdir
  doesn't, flat layout doesn't, non-directory `ios` entry doesn't).
  149/149 SPM tests pass.

Author: chrfalch

packages/react-native/react-native.config.js

@@ -165,6 +165,31 @@ const spmCommand /*: Command */ = {
       description:
         'JS entry file relative to app root (default: package.json "main" or index.js).',
     },
+    {
+      name: '--project',
+      description:
+        '[clean] Also remove Package.swift and <App>-SPM.xcodeproj/.',
+    },
+    {
+      name: '--derivedData',
+      description:
+        "[clean] Also remove this app's DerivedData (~/Library/Developer/Xcode/DerivedData/<App>-SPM-*).",
+    },
+    {
+      name: '--cache',
+      description:
+        '[clean] Also remove the cached xcframework slot for the current resolved version.',
+    },
+    {
+      name: '--all',
+      description:
+        '[clean] Shorthand for --project --derivedData --cache.',
+    },
+    {
+      name: '--yes',
+      description:
+        '[clean] Skip the confirmation prompt for destructive scopes.',
+    },
     // Workaround for @react-native-community/cli: when any positional equals
     // "init" (including our `spm init` action), the CLI naively appends
     // `--platform-name <platform>` to argv. Accept and ignore it so commander
@@ -198,6 +223,11 @@ const spmCommand /*: Command */ = {
       ['skipDownload', '--skip-download'],
       ['forceDownload', '--force-download'],
       ['skipXcodeproj', '--skip-xcodeproj'],
+      ['project', '--project'],
+      ['derivedData', '--derived-data'],
+      ['cache', '--cache'],
+      ['all', '--all'],
+      ['yes', '--yes'],
     ];
     for (const [key, flag] of boolOpts) {
       if (args[key]) {