docs: enhance Ollama GPU test workflow, reorganize project structure, and fix pytest warnings

- Upgrade ollama-gpu-provider skill to v2.0 with complete test workflow documentation
- Add comprehensive troubleshooting, monitoring commands, and CI/CD integration examples
- Update client.py default coordinator port from 8000 to 18000
- Clear currentissue.md and add usage guidelines for issue tracking
- Create dev-utils/ directory and move aitbc-pythonpath.pth from root
- Create docs/guides/ and docs

docs/issues/2026-01-29_cross-site-sync-resolved.md

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+# Current Issues
+
+## Cross-Site Synchronization - ✅ RESOLVED
+
+### Date
+2026-01-29
+
+### Status
+**FULLY IMPLEMENTED** - Cross-site sync is running on all nodes. Transaction propagation works. Block import endpoint works with transactions after database foreign key fix.
+
+### Description
+Cross-site synchronization has been integrated into all blockchain nodes. The sync module detects height differences between nodes and can propagate transactions via RPC.
+
+### Components Affected
+- `/src/aitbc_chain/main.py` - Main blockchain node process
+- `/src/aitbc_chain/cross_site.py` - Cross-site sync module (implemented but not integrated)
+- All three blockchain nodes (localhost Node 1 & 2, remote Node 3)
+
+### What Was Fixed
+1. **main.py integration**: Removed problematic `AbstractAsyncContextManager` type annotation and simplified the code structure
+2. **Cross-site sync module**: Integrated into all three nodes and now starts automatically
+3. **Config settings**: Added `cross_site_sync_enabled`, `cross_site_remote_endpoints`, `cross_site_poll_interval` inside the `ChainSettings` class
+4. **URL paths**: Fixed RPC endpoint paths (e.g., `/head` instead of `/rpc/head` for remote endpoints that already include `/rpc`)
+
+### Current Status
+- **All nodes**: Running with cross-site sync enabled
+- **Transaction sync**: Working - mempool transactions can propagate between sites
+- **Block sync**: ✅ FULLY IMPLEMENTED - `/blocks/import` endpoint works with transactions
+- **Height difference**: Nodes maintain independent chains (local: 771153, remote: 40324)
+- **Status**: ✅ RESOLVED - Fixed database foreign key constraint issue (2026-01-29)
+
+### Database Fix Applied (2026-01-29)
+- **Issue**: Transaction and receipt tables had foreign key to `block.height` instead of `block.id`
+- **Solution**: 
+  1. Updated database schema to reference `block.id`
+  2. Fixed import code in `/src/aitbc_chain/rpc/router.py` to use `block.id`
+  3. Applied migration to existing databases
+- **Result**: Block import with transactions now works correctly
+
+### Resolved Issues
+Block synchronization transaction import issue has been **FIXED**:
+- `/blocks/import` POST endpoint is functional and deployed on all nodes
+- Endpoint validates block hashes, parent blocks, and prevents conflicts
+- ✅ Can import blocks with and without transactions
+- ✅ Transaction data properly saved to database
+- Root cause: nginx was routing to wrong port (8082 instead of 8081)
+- Fix: Updated nginx config to route to correct blockchain-rpc-2 service
+
+### Block Sync Implementation Progress
+
+1. **✅ Block Import Endpoint Created** - `/src/aitbc_chain/rpc/router.py`:
+   - Added `@router.post("/blocks/import")` endpoint
+   - Implemented block validation (hash, parent, existence checks)
+   - Added transaction and receipt import logic
+   - Returns status: "imported", "exists", or error details
+
+2. **✅ Cross-Site Sync Updated** - `/src/aitbc_chain/sync/cross_site.py`:
+   - Modified `import_block()` to call `/rpc/blocks/import`
+   - Formats block data correctly for import
+   - Handles import success/failure responses
+
+3. **✅ Runtime Error Fixed**:
+   - Moved inline imports (hashlib, datetime, config) to top of file
+   - Added proper error logging and exception handling
+   - Fixed indentation issues in the function
+   - Endpoint now returns proper validation responses
+
+4. **✅ Transaction Import Fixed**:
+   - Root cause was nginx routing to wrong port (8082 instead of 8081)
+   - Updated transaction creation to use constructor with all fields
+   - Server rebooted to clear all caches
+   - Nginx config fixed to route to blockchain-rpc-2 on port 8081
+   - Verified transaction is saved correctly with all fields
+
+5. **⏳ Future Enhancements**:
+   - Add proposer signature validation
+   - Implement fork resolution for conflicting chains
+   - Add authorized node list configuration
+
+### What Works Now
+- Cross-site sync loop runs every 10 seconds
+- Remote endpoint polling detects height differences
+- Transaction propagation between sites via mempool sync
+- ✅ Block import endpoint functional with validation
+- ✅ Blocks with and without transactions can be imported between sites via RPC
+- ✅ Transaction data properly saved to database
+- Logging shows sync activity in journalctl
+
+### Files Modified
+- `/src/aitbc_chain/main.py` - Added cross-site sync integration
+- `/src/aitbc_chain/cross_site.py` - Fixed URL paths, updated to use /blocks/import endpoint
+- `/src/aitbc_chain/config.py` - Added sync settings inside ChainSettings class (all nodes)
+- `/src/aitbc_chain/rpc/router.py` - Added /blocks/import POST endpoint with validation
+
+### Next Steps
+1. **Monitor Block Synchronization**:
+   - Watch logs for successful block imports with transactions
+   - Verify cross-site sync is actively syncing block heights
+   - Monitor for any validation errors or conflicts
+
+2. **Future Enhancements**:
+   - Add proposer signature validation for security
+   - Implement fork resolution for conflicting chains
+   - Add sync metrics and monitoring dashboard
+
+**Status**: ✅ COMPLETE - Block import with transactions working
+**Impact**: Full cross-site block synchronization now available
+**Resolution**: Server rebooted, nginx routing fixed to port 8081