fix: address PR review feedback for MCP tools support

- Avoid logging sensitive cfg.Args in ConnectServer; log args_count instead
- Sanitize server/tool name components in MCPTool.Name() to ensure valid
  identifiers for downstream providers (lowercase, [a-z0-9_-] only)
- Add slack as 5th MCP server example in config.example.json
- Move Dockerfile.full and docker-compose.full.yml into docker/ directory
  for consistency with existing docker/Dockerfile and docker/docker-compose.yml
- Fix all Makefile docker-* targets to reference correct compose file paths
- Fix docker/docker-compose.full.yml build context (.. ) and volume paths
- Fix scripts/test-docker-mcp.sh compose file path and replace cowsay test
  with actual @modelcontextprotocol/server-filesystem MCP server test

config/config.example.json

@@ -279,6 +279,18 @@
             "@modelcontextprotocol/server-postgres",
             "postgresql://user:password@localhost/dbname"
           ]
+        },
+        "slack": {
+          "enabled": false,
+          "command": "npx",
+          "args": [
+            "-y",
+            "@modelcontextprotocol/server-slack"
+          ],
+          "env": {
+            "SLACK_BOT_TOKEN": "YOUR_SLACK_BOT_TOKEN",
+            "SLACK_TEAM_ID": "YOUR_SLACK_TEAM_ID"
+          }
         }
       }
     },