Phase 6: Multi-Connector Resolution

## Goal

Allow multiple connectors to run on the same URL and merge results.

## Tasks

- [ ] **findAllForUrl usage** - Use registry.findAllForUrl instead of findForUrl
- [ ] **Result merging** - Merge representations, annotations from multiple connectors
- [ ] **Priority system** - Higher-priority connectors' suggestions take precedence
- [ ] **UI for multiple proposals** - Show merged proposal with source attribution

## Files to Modify

- `src/connectors/resolver.ts` (use findAllForUrl, merge results)
- `src/connectors/registry.ts` (add priority system)
- `src/ui/proposal-review.ts` (show merged proposal with source attribution)

## Acceptance Criteria

- Multiple connectors can run on the same URL
- Results are merged correctly with source attribution
- Higher-priority connectors' suggestions take precedence
- UI shows merged proposal with source attribution
- All merging logic is tested and working

## Testing

- Run multiple connectors on the same URL and verify results are merged correctly
- Verify higher-priority connectors' suggestions take precedence
- Verify UI shows merged proposal with source attribution

Start by reading src/connectors/resolver.ts, src/connectors/registry.ts, and src/ui/proposal-review.ts to trace current connector lookup, result handling, and proposal display. Run the existing tests before changing behavior, then add coverage for multiple connectors, priority precedence, merging, and source attribution. Done means the acceptance criteria pass and all merging logic is tested.

Written by the indexing model from the issue text.