Before:
startup → load extensions → require() optional deps → crash ❌

After:
startup → load extensions → lazy load deps → skip if missing → continue ✅

## Security Impact (required)

- New permissions/capabilities? No  
- Secrets/tokens handling changed? No  
- New/changed network calls? No  
- Command/tool execution surface changed? No  
- Data access scope changed? No  

---

## Repro + Verification

### Environment

- OS: Arch Linux x86_64 
- Kernel: 6.19.11-arch1-1
- Runtime/container: Node v22 .22.2
- Model/provider: N/A  
- Integration/channel (if any): Feishu, Nostr  
- Relevant config (redacted): default install (no optional deps installed  

### Steps

1. Install CLI globally: `npm install -g openclaw`  
2. Run `openclaw`  
3. Observe startup behavior  

### Expected

- CLI starts successfully  
- Optional extensions remain inactive if dependencies are missing  

### Actual

- CLI crashes with `MODULE_NOT_FOUND` (before fix)  

---

## Evidence

- [x] Runtime error reproduced before fix  
- [x] CLI starts successfully after fix  

---

## Human Verification (required)

- Verified scenarios:
  - global install without optional dependencies  
  - extension initialization does not crash  
  - features work when dependencies are present  

- Edge cases checked:
  - missing single dependency  
  - missing all optional dependencies  

- What you did **not** verify:
  - all platform combinations  
  - bundled distribution edge cases  

---

## Review Conversations

- [ ] I replied to or resolved every bot review conversation I addressed in this PR.  
- [ ] I left unresolved only the conversations that still need reviewer or maintainer judgment.  

---

## Compatibility / Migration

- Backward compatible? Yes  
- Config/env changes? No  
- Migration needed? No  

---

## Risks and Mitigations

- Risk:  
  Lazy loading may mask missing dependency errors until runtime usage  

  - Mitigation:  
    Explicit error handling and graceful fallback ensures predictable behavior  

---

## Summary of Changes

- Replaced top-level imports in Feishu and Nostr extensions with lazy-loading logic  
- Added guarded loaders for optional dependencies  
- Ensured extensions disable gracefully when dependencies are unavailable  
- Fixed scoping issues introduced during refactor (Nostr helper placement)  
- Cleaned up types and lint issues to satisfy strict pre-commit hooks  

---

## Technical Details

### Feishu Extension

- Implemented `loadFeishuSdkSync()` using `createRequire(import.meta.url)`  
- Preserves synchronous API surface while deferring module resolution  
- Deferred SDK side-effects (e.g., User-Agent patching) until successful load  
- Introduced `MissingOptionalDependencyError` for controlled failure handling  

### Nostr Extension

- Implemented hybrid loader:
  - `await import()` for ESM + test compatibility (Vitest mocking)  
  - fallback to `require()` for runtime environments  

- Added normalization layer to handle:
  - ESM namespace imports  
  - `.default` export variations  

- Fixed scoping issue by relocating `sendEncryptedDm` inside runtime closure  

### Design Considerations

- Avoided top-level imports to prevent eager dependency resolution  
- Maintained compatibility with:
  - ESM environments  
  - CommonJS runtime  
  - Vitest mocking behavior  

---

## Testing Performed

- Ran local test suites → all passing  
- Ran TypeScript checks (`pnpm tsgo`) → no errors  
- Verified CLI startup:
  - without optional dependencies → no crash  
  - with dependencies installed → functionality intact

## Changed files

- `src/commands/doctor-config-flow.ts` (modified, +5/-0)
- `src/config/io.ts` (modified, +24/-12)
- `src/flows/doctor-health-contributions.ts` (modified, +125/-1)