Fix Docker Swarm discovery network name mismatch

- Changed NetworkName from 'chorus_default' to 'chorus_net'
- This matches the actual network 'CHORUS_chorus_net' (service prefix added automatically)
- Fixes discovered_count:0 issue - now successfully discovering all 25 agents
- Updated IMPLEMENTATION-SUMMARY with deployment status

Result: All 25 CHORUS agents now discovered successfully via Docker Swarm API

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

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

go.mod

@@ -13,7 +13,6 @@ require (
 	github.com/golang-jwt/jwt/v5 v5.3.0
 	github.com/golang-migrate/migrate/v4 v4.17.0
 	github.com/google/uuid v1.6.0
-	github.com/gorilla/mux v1.8.1
 	github.com/jackc/pgx/v5 v5.5.2
 	github.com/kelseyhightower/envconfig v1.4.0
 	github.com/rs/zerolog v1.32.0