feat: Single-DB Multi-Agent Isolation with Shared Memory Support

[witplay]

• Add 'agent_id' column to SQLite store for logical isolation.
• Logic: instruction/persona types -> 'shared' (global), episodic -> '{profile}' (private).
• Update Hermes Plugin to prefix session keys with 'agent:{profile}:'.
• Update Gateway Recall to include 'prependContext' (L1 memories) in response.
• Implement agent identity filtering in FTS and Vector search.
• Includes automatic migration logic for legacy data.

Description | 描述

This PR implements Single-DB Multi-Agent Isolation with a Shared Memory area, solving the data mixing issue in multi-profile setups (Issue #31347).

💡 Core Design

Instead of using multiple databases (heavy), we use a single SQLite database with an agent_id column:

1. Shared Memory: instruction and persona types are marked as shared. All profiles (default, xiaoxiao, zhi, etc.) share user profile and global rules.
2. Private Memory: episodic types are strictly isolated by agent:{profile}.
3. Migration: Includes logic to migrate legacy data (defaulting to default profile).

📂 Modified Files

• hermes-plugin/...: Prefix session keys with agent:{profile}:.
• src/core/store/sqlite.ts: Add agent_id column, implement shared/private logic, filter FTS/Vector search.
• src/core/hooks/auto-recall.ts: Parse sessionKey to pass agentId.
• src/gateway/server.ts: Include prependContext (L1 memories) in recall response.

🛡️ Benefits

• Zero Overhead: Single file management, easy backup/migration.
• Clean Logic: Solves the "share persona vs isolate context" dilemma cleanly.

Related Issue | 关联 Issue

Related to #31347

Change Type | 修改类型

• Bug fix | Bug 修复A
• New feature | 新功能
• Documentation update | 文档更新
• Code optimization | 代码优化

Self-test Checklist | 自测清单

• Verified locally | 本地验证通过
• No existing features affected | 无影响现有功能

Additional Notes | 其他说明

This approach is lightweight compared to the proposed multi-DB solution and works perfectly with SQLite's local architecture.