Fix duplicate REPORTS relationships in Neo4j backend (v0.36.1)

- Change processReport() to use MERGE instead of CREATE for REPORTS
  relationships, deduplicating by (reporter, reported, report_type)
- Add ON CREATE/ON MATCH clauses to preserve newest event data while
  preventing duplicate relationships
- Add getExistingReportEvent() helper to check for existing reports
- Add markReportEventSuperseded() to track superseded events
- Add v4 migration migrateDeduplicateReports() to clean up existing
  duplicate REPORTS relationships in databases
- Add comprehensive tests: TestReportDeduplication with subtests for
  deduplication, different types, and superseded event tracking
- Update WOT_SPEC.md with REPORTS deduplication behavior and correct
  property names (report_type, created_at, created_by_event)
- Bump version to v0.36.1

Fixes: https://git.nostrdev.com/mleku/next.orly.dev/issues/16

Files modified:
- pkg/neo4j/social-event-processor.go: MERGE-based deduplication
- pkg/neo4j/migrations.go: v4 migration for duplicate cleanup
- pkg/neo4j/social-event-processor_test.go: Deduplication tests
- pkg/neo4j/WOT_SPEC.md: Updated REPORTS documentation
- pkg/version/version: Bump to v0.36.1

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

pkg/version/version

@@ -1 +1 @@
-v0.36.0
+v0.36.1