feat: session memory persistence and injection

[OneStepAt4time]

Problem

Every CC session starts with zero context. No memory between sessions. When Hep works on the same codebase across sessions, nothing is remembered.

Solution

Aegis saves a summary of each completed CC session (what was done, errors encountered, decisions made, files modified) and makes it available to future sessions on the same project.

Implementation

• On session close, extract memory summary from transcript JSONL
• Save to .aegis/session-memory/<session-id>.json
• On new session creation for same workDir, read recent memories
• Inject as preamble in initial CC prompt
• MCP tools: read_memory(project), write_memory(project, key, value), search_memory(project, query)
• HTTP: GET /v1/memory/:project, POST /v1/memory/:project

Acceptance Criteria

• Session memory auto-saved on session close
• New sessions receive relevant context from same project
• Memory readable via MCP tools and HTTP API
• Memory scope: per-project (workDir level)

Reference

• OMC: src/services/SessionMemory/ — project memory with auto-capture
• CC: src/services/extractMemories/ — pattern extraction from sessions

[OneStepAt4time]

Duplicate of #783 (session memory bridge — superseded)