Refactor kafka to pure Go (franz-go), fix DBC stubs, update Dockerfile

pkg/dbc/README.md

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+# DBC Package
+
+CAN database (DBC) signal definitions and parsing utilities.
+
+## Structure
+
+- `models/` - Core types (DBCCollection, CANMessage, CANSignal)
+- `state/` - State tracking for CAN signals
+- `diagnostics/` - Diagnostic signal handling
+- `fm29_*/`, `n60/` - Generated packages from DBC files (stubs by default)
+
+## Generated Packages
+
+The `fm29_*` and `n60` packages contain CAN signal definitions generated from DBC files. By default, these are stubs that return empty collections.
+
+To generate real definitions, you need:
+1. DBC source files (from CEC-Common repo or equivalent)
+2. The `cantool` from `pkg/can-go`
+
+## Generating DBC Code
+
+```bash
+# From cloud-services root
+go run ./pkg/can-go/cmd/cantool generate /path/to/dbc/files ./pkg/dbc
+```
+
+Or use the generate script:
+```bash
+./scripts/generate-dbc.sh /path/to/dbc/files
+```
+
+## When Do You Need Real DBC Packages?
+
+- **Gateway**: Uses only `dbc/models` - stubs are fine
+- **Optimus**: Needs real DBC for CAN signal parsing
+- **Ditto**: Needs real DBC for digital twin state
+- **Beacon**: Needs real DBC for diagnostic alerts
+
+## Adding New DBC Versions
+
+1. Add DBC files to source directory
+2. Run cantool generate
+3. Update `new_dbc_collection.go` to include new version