feat(memory): #87 project setup & core architecture

Implements Sub-Issue #87 of Issue #62 (Agent Memory System).

Core infrastructure:
- memory/types.py: Type definitions for all memory types (Working, Episodic,
  Semantic, Procedural) with enums for MemoryType, ScopeLevel, Outcome
- memory/config.py: MemorySettings with MEM_ env prefix, thread-safe singleton
- memory/exceptions.py: Comprehensive exception hierarchy for memory operations
- memory/manager.py: MemoryManager facade with placeholder methods

Directory structure:
- working/: Working memory (Redis/in-memory) - to be implemented in #89
- episodic/: Episodic memory (experiences) - to be implemented in #90
- semantic/: Semantic memory (facts) - to be implemented in #91
- procedural/: Procedural memory (skills) - to be implemented in #92
- scoping/: Scope management - to be implemented in #93
- indexing/: Vector indexing - to be implemented in #94
- consolidation/: Memory consolidation - to be implemented in #95

Tests: 71 unit tests for config, types, and exceptions
Docs: Comprehensive implementation plan at docs/architecture/memory-system-plan.md

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/services/memory/__init__.py

@@ -0,0 +1,136 @@
+"""
+Agent Memory System
+
+Multi-tier cognitive memory for AI agents, providing:
+- Working Memory: Session-scoped ephemeral state (Redis/In-memory)
+- Episodic Memory: Experiential records of past tasks (PostgreSQL)
+- Semantic Memory: Learned facts and knowledge (PostgreSQL + pgvector)
+- Procedural Memory: Learned skills and procedures (PostgreSQL)
+
+Usage:
+    from app.services.memory import (
+        MemoryManager,
+        MemorySettings,
+        get_memory_settings,
+        MemoryType,
+        ScopeLevel,
+    )
+
+    # Create a manager for a session
+    manager = MemoryManager.for_session(
+        session_id="sess-123",
+        project_id=uuid,
+    )
+
+    async with manager:
+        # Working memory
+        await manager.set_working("key", {"data": "value"})
+        value = await manager.get_working("key")
+
+        # Episodic memory
+        episode = await manager.record_episode(episode_data)
+        similar = await manager.search_episodes("query")
+
+        # Semantic memory
+        fact = await manager.store_fact(fact_data)
+        facts = await manager.search_facts("query")
+
+        # Procedural memory
+        procedure = await manager.record_procedure(procedure_data)
+        procedures = await manager.find_procedures("context")
+"""
+
+# Configuration
+from .config import (
+    MemorySettings,
+    get_default_settings,
+    get_memory_settings,
+    reset_memory_settings,
+)
+
+# Exceptions
+from .exceptions import (
+    CheckpointError,
+    EmbeddingError,
+    MemoryCapacityError,
+    MemoryConflictError,
+    MemoryConsolidationError,
+    MemoryError,
+    MemoryExpiredError,
+    MemoryNotFoundError,
+    MemoryRetrievalError,
+    MemoryScopeError,
+    MemorySerializationError,
+    MemoryStorageError,
+)
+
+# Manager
+from .manager import MemoryManager
+
+# Types
+from .types import (
+    ConsolidationStatus,
+    ConsolidationType,
+    Episode,
+    EpisodeCreate,
+    Fact,
+    FactCreate,
+    MemoryItem,
+    MemoryStats,
+    MemoryStore,
+    MemoryType,
+    Outcome,
+    Procedure,
+    ProcedureCreate,
+    RetrievalResult,
+    ScopeContext,
+    ScopeLevel,
+    Step,
+    TaskState,
+    WorkingMemoryItem,
+)
+
+__all__ = [
+    "CheckpointError",
+    "ConsolidationStatus",
+    "ConsolidationType",
+    "EmbeddingError",
+    "Episode",
+    "EpisodeCreate",
+    "Fact",
+    "FactCreate",
+    "MemoryCapacityError",
+    "MemoryConflictError",
+    "MemoryConsolidationError",
+    # Exceptions
+    "MemoryError",
+    "MemoryExpiredError",
+    "MemoryItem",
+    # Manager
+    "MemoryManager",
+    "MemoryNotFoundError",
+    "MemoryRetrievalError",
+    "MemoryScopeError",
+    "MemorySerializationError",
+    # Configuration
+    "MemorySettings",
+    "MemoryStats",
+    "MemoryStorageError",
+    # Types - Abstract
+    "MemoryStore",
+    # Types - Enums
+    "MemoryType",
+    "Outcome",
+    "Procedure",
+    "ProcedureCreate",
+    "RetrievalResult",
+    # Types - Data Classes
+    "ScopeContext",
+    "ScopeLevel",
+    "Step",
+    "TaskState",
+    "WorkingMemoryItem",
+    "get_default_settings",
+    "get_memory_settings",
+    "reset_memory_settings",
+]