refactor(create): address round-2 simplify review

Four small quality wins plus the big one — shared snap-test helper:

- `packages/tools/src/snap-test.ts`: expose `SNAP_CASES_DIR` as an env
  var pointing at the source cases directory. Lets fixtures reference
  shared helper scripts under `<casesDir>/.shared/` without duplicating
  them into every fixture. The dot-prefix keeps the shared dir invisible
  to the test iterator (which already skips dotfiles).

- Collapse the 4 byte-identical `mock-server.mjs` copies (89 LOC each)
  into a single `packages/cli/snap-tests/.shared/mock-npm-registry.mjs`.
  Each fixture's `steps.json` now invokes it via
  `node $SNAP_CASES_DIR/.shared/mock-npm-registry.mjs -- vp create ...`.
  Bug fixes to the mock registry now apply to all consumers at once.

- `org-picker.ts`: drop the hard-coded "inside a monorepo" message from
  the empty-filter branch. Move the context-specific info note to the
  caller (`org-resolve.ts`), gated on the exact predicate that produced
  the empty filter. Keeps the picker context-agnostic so future filters
  don't need to update picker internals.

- `templates/bundled.ts`: drop the "@org/create package" presumption
  from the ENOENT error message. The executor is generic — it only
  knows about `localPath` — so the message follows suit.

- `org-picker.spec.ts`: simplify the escape-hatch round-trip assertion
  by dropping the externally-captured `escapeValue` variable. The
  mockImplementation return value is sufficient on its own.

Snaps regenerated (only the command line in the first row changed to
reference the shared helper via $SNAP_CASES_DIR); output bodies
byte-identical; full unit suite still 263/263.

Net: -267 LOC across 17 files.

Author: fengmk2

…tests/create-org-bundled/mock-server.mjs …snap-tests/.shared/mock-npm-registry.mjspackages/cli/snap-tests/create-org-bundled/mock-server.mjs renamed to packages/cli/snap-tests/.shared/mock-npm-registry.mjs packages/cli/snap-tests/create-org-bundled/mock-server.mjs renamed to packages/cli/snap-tests/.shared/mock-npm-registry.mjs

@@ -1,4 +1,4 @@
-> node mock-server.mjs -- vp create @your-org/demo --no-interactive --directory my-demo-app # bundled template: extract tarball, copy subdir
+> node $SNAP_CASES_DIR/.shared/mock-npm-registry.mjs -- vp create @your-org/demo --no-interactive --directory my-demo-app # bundled template: extract tarball, copy subdir
 
 selected 'demo' from @your-org/create
 ◇ Scaffolded my-demo-app

packages/cli/snap-tests/create-org-bundled/snap.txt

@@ -1,6 +1,6 @@
 {
   "commands": [
-    "node mock-server.mjs -- vp create @your-org/demo --no-interactive --directory my-demo-app # bundled template: extract tarball, copy subdir",
+    "node $SNAP_CASES_DIR/.shared/mock-npm-registry.mjs -- vp create @your-org/demo --no-interactive --directory my-demo-app # bundled template: extract tarball, copy subdir",
     "cat my-demo-app/package.json # verify package.json name was rewritten",
     "cat my-demo-app/src/index.ts # verify bundled source copied",
     "ls my-demo-app/README.md # verify README copied"

packages/cli/snap-tests/create-org-bundled/steps.json

@@ -1,4 +1,4 @@
-[1]> node mock-server.mjs -- vp create @your-org --no-interactive # invalid manifest -> schema error
+[1]> node $SNAP_CASES_DIR/.shared/mock-npm-registry.mjs -- vp create @your-org --no-interactive # invalid manifest -> schema error
 
 @your-org/create: vp.templates[0].template must be a non-empty string
 Failed to resolve org template manifest

packages/cli/snap-tests/create-org-invalid-manifest/mock-server.mjs

@@ -1,5 +1,5 @@
 {
   "commands": [
-    "node mock-server.mjs -- vp create @your-org --no-interactive # invalid manifest -> schema error"
+    "node $SNAP_CASES_DIR/.shared/mock-npm-registry.mjs -- vp create @your-org --no-interactive # invalid manifest -> schema error"
   ]
 }

packages/cli/snap-tests/create-org-invalid-manifest/snap.txt

@@ -1,4 +1,4 @@
-[1]> node mock-server.mjs -- vp create @your-org --no-interactive # inside monorepo, hides monorepo:true entries + shows omitted footer
+[1]> node $SNAP_CASES_DIR/.shared/mock-npm-registry.mjs -- vp create @your-org --no-interactive # inside monorepo, hides monorepo:true entries + shows omitted footer
 error: vp create @your-org requires a template selection in non-interactive mode.
 
 available templates from @your-org/create:

packages/cli/snap-tests/create-org-invalid-manifest/steps.json

@@ -1,5 +1,5 @@
 {
   "commands": [
-    "node mock-server.mjs -- vp create @your-org --no-interactive # inside monorepo, hides monorepo:true entries + shows omitted footer"
+    "node $SNAP_CASES_DIR/.shared/mock-npm-registry.mjs -- vp create @your-org --no-interactive # inside monorepo, hides monorepo:true entries + shows omitted footer"
   ]
 }