[Embeds] Restore watcher bindings with instance-scoped containers

[techmahedy]

Pull Request Checklist

Q	A
Branch?	4.x
Bug fix?	yes
New feature?	no
Deprecations?	no
Issues	-
License	MIT

Description

1. Fix embedded property watcher resolution after Doppar moved container bindings to instance scope.
2. Remove the static container boot cache from Embeddable.
3. Recreate watcher bindings when the active container is replaced or flushed.
4. Preserve semantic search behavior across brute-force, pgvector, and Redis drivers.

Checklist

• Tests have been added or updated
• Documentation has been updated if necessary
• Code follows the project coding standards
• All tests pass locally