feat(paperclip): add hindsight-paperclip TypeScript integration

[benfrank241]

Summary

• New hindsight-paperclip npm package providing long-term memory for Paperclip AI agents
• recall() / retain() functions for use in heartbeat lifecycle hooks (HTTP and Process adapters)
• createMemoryMiddleware() for Express HTTP adapter agents — auto-recalls before each request, auto-retains agent output after each response
• Bank ID strategy maps Paperclip's company/agent isolation to Hindsight banks: paperclip::{companyId}::{agentId} (configurable granularity)
• 27 unit tests covering bank derivation, recall, and retain (all passing)
• Docs page at sdks/integrations/paperclip added to sidebar

Package structure

hindsight-integrations/paperclip/
├── src/
│   ├── index.ts         # Main exports
│   ├── client.ts        # Hindsight HTTP client (native fetch, no deps)
│   ├── config.ts        # PaperclipMemoryConfig + loadConfig()
│   ├── bank.ts          # Bank ID derivation
│   ├── recall.ts        # recall() function
│   ├── retain.ts        # retain() function
│   └── middleware.ts    # createMemoryMiddleware() for Express
└── tests/
    ├── bank.test.ts
    ├── recall.test.ts
    └── retain.test.ts

Test plan

• npm run build — TypeScript compiles cleanly
• npm test — 27 tests pass (bank derivation, recall, retain)
• Integration smoke test against a live Hindsight instance (7/7 passing)
• End-to-end test with a Paperclip HTTP adapter agent