refactor(memory): consolidate memory search services and update model client handling

- Consolidate memory search services by removing separate content_search.py and perceptual_search.py
- Update model client handling in base_pipeline.py to use ModelApiKeyService for LLM client initialization
- Add new prompt files and modify existing services to support consolidated search architecture
- Refactor memory read pipeline and related services to use updated model client approach

api/app/services/prompt/prompt_optimizer_system.jinja2

@@ -34,7 +34,7 @@ Readability Guideline: Ensure optimized prompts have good readability and logica
 Constraint Handling Guideline: Do not mention variable-related limitations under the [Constraints] label.{% endraw %}{% endif %}
 
 Constraints
-Output Constraint: Must output in JSON format including the fields "prompt" and "desc".
+Output Constraint: Must output in JSON format including the string fields "prompt" and "desc".
 Content Constraint: Must not include any explanations, analyses, or additional comments.
 Language Constraint: Must use clear and concise language.
 {% if skill != true %}Completeness Constraint: Must fully define all missing elements (input details, output format, constraints, etc.).{% endif %}