fix(search): delete regex bare-JSON-prefix rewrite, use default subpaths

The regex rewrite that turned bare notes:/custom_fields: prefixes into
their subpath spelling was blind to quoting: content:"payment notes:
none" was silently rewritten mid-phrase into a notes-field search and
matched zero documents. whoosh-compat's FieldSpec now supports a
default subpath per JSON field (SubpathSpec(default=True)), which
resolves during parsing where quoting is already understood, so the
pre-parse string rewrite is no longer needed.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/documents/tests/search/test_acceptance.py

@@ -354,77 +354,6 @@ class TestUnquotedDateKeywordPhrases:
             assert _matched_ids(backend, "title:previous month") == {wordy.pk}
 
 
-class TestBareJsonFieldPrefixes:
-    """ "notes:foo"/"custom_fields:foo" were valid fielded searches before
-    this migration. whoosh-compat's registry only exposes them as JSON
-    subpaths, so parse_user_query rewrites the bare prefixes live: notes:
-    -> notes.note:, custom_fields: -> custom_fields.value:."""
-
-    def test_bare_notes_prefix_searches_note_text(
-        self,
-        backend: TantivyBackend,
-    ) -> None:
-        alice = User.objects.create_user(username="alice")
-        with_note = Document.objects.create(
-            title="Has note",
-            content="x",
-            checksum="bare-notes-with",
-        )
-        Note.objects.create(document=with_note, user=alice, note="crocodile")
-        backend.add_or_update(with_note)
-        # This document's CONTENT contains the words a demoted text search
-        # would match; it must NOT match once the prefix addresses notes.
-        _index(
-            backend,
-            title="Notes about things",
-            content="notes crocodile mention",
-            checksum="bare-notes-decoy",
-        )
-        assert _matched_ids(backend, "notes:crocodile") == {with_note.pk}
-
-    def test_bare_custom_fields_prefix_searches_values(
-        self,
-        backend: TantivyBackend,
-    ) -> None:
-        field = CustomField.objects.create(
-            name="Policy Number",
-            data_type=CustomField.FieldDataType.STRING,
-        )
-        with_value = Document.objects.create(
-            title="Has field",
-            content="x",
-            checksum="bare-cf-with",
-        )
-        CustomFieldInstance.objects.create(
-            document=with_value,
-            field=field,
-            value_text="crocodile",
-        )
-        backend.add_or_update(with_value)
-        _index(
-            backend,
-            title="Custom things",
-            content="custom fields crocodile",
-            checksum="bare-cf-decoy",
-        )
-        assert _matched_ids(backend, "custom_fields:crocodile") == {with_value.pk}
-
-    def test_subpath_spellings_are_untouched(
-        self,
-        backend: TantivyBackend,
-    ) -> None:
-        bob = User.objects.create_user(username="bob")
-        doc = Document.objects.create(
-            title="Bob note",
-            content="x",
-            checksum="bare-subpath",
-        )
-        Note.objects.create(document=doc, user=bob, note="remark")
-        backend.add_or_update(doc)
-        assert _matched_ids(backend, "notes.user:bob") == {doc.pk}
-        assert _matched_ids(backend, "notes.note:remark") == {doc.pk}
-
-
 class TestFieldAliases:
     """type:/path: are registry aliases for document_type:/storage_path:.
     The only other alias coverage is parse-shape; these prove resolution