Fix embedded documents: recursion crash, .all/.count, honest spec exclusion

Live-run finding: the full suite against Couchbase was 423 examples with 17
failures — all in embedding_spec. The session report claimed embedded specs
were 'excluded by design', but the exclusion filter targeted a :embedding tag
no example carries, so the file ran (and failed) all along.

Three fixes:
- HasManyEmbedded::Property#build wired parent_object before installing the
  collection ivar on the parent; parent_object= reaches back into the parent's
  collection getter, which re-entered build -> SystemStackError on any access
  to embedded documents loaded from the database. Install the ivar first.
- EmbeddedClass.all / .count referenced raw JS views (all_documents /
  all_documents_for_count) that the N1QL port silently drops, so .all returned
  [] and .count raised NoMethodError. Rebuilt them by enumerating the parent
  documents (same work as the old view scan, client-side; an UNNEST query can
  replace it later).
- Only reverse lookups (N1QL on a foreign key inside an embedded array) remain
  unsupported: tagged :embedded_in_reverse_lookup and excluded in spec_helper
  with an explanatory comment, replacing the broken :embedding filter line.

embedding_spec.rb: 16 examples, 0 failures against live Couchbase 8.0.1 CE.

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

spec/spec_helper.rb

@@ -14,6 +14,10 @@ RSpec.configure do |config|
   config.expect_with(:rspec) { |c| c.syntax = [:expect, :should] }
   config.color = true
   config.filter_run_excluding :couchdb_only # CouchDB-mechanic specs with no Couchbase equivalent
+  # Reverse lookups into embedded documents (querying a foreign key held
+  # *inside* an embedded array element) are not implemented on Couchbase —
+  # they would need an UNNEST-based query path. Documented gap.
+  config.filter_run_excluding :embedded_in_reverse_lookup
 
   config.before(:suite) do
     SimplyBased.database_url = COUCHBASE_URL