test: MCP server test suite + README documentation

[OneStepAt4time]

M1.4 — Testing + Documentation

Parent: #440 (Roadmap)
Milestone: M1 — MCP Server Complete
Depends on: #441, #442, #443

Testing

• Unit tests for all MCP tools (mock AegisClient, verify JSON-RPC responses)
• Unit tests for all MCP resources
• Unit tests for all MCP prompts
• Integration test: start MCP server via stdio, call tools/list, verify all tools present
• Error handling tests: invalid session ID, server down, auth failure

Documentation

• README section: "## MCP Server"
  • What it is
  • How to start: aegis-bridge mcp
  • How to add to Claude Code: claude mcp add --scope user aegis -- npx aegis-bridge mcp
  • How to add to .mcp.json
  • Full tool list with descriptions
  • Full resource list
  • Full prompt list
• Example .mcp.json config snippet

Acceptance criteria

• ≥80% code coverage on mcp-server.ts
• README MCP section complete and accurate
• npx aegis-bridge mcp works out of the box after npm install