Bundle kaya-otel in the Docker image

The tavolo-app otel extra was never installed: requirements.txt was
locked without it and the Dockerfile installs the local distributions
with --no-deps, so any container with OTEL_ENABLED set died at import
with "kaya-otel is not installed".

Add the extra's full closure (kaya-otel plus its OpenTelemetry/protobuf
dependencies) to the pinned lock and refresh the comments that claimed
the extra had to be added separately.

server/README.md

@@ -81,7 +81,7 @@ All configuration comes from environment variables (see `.env.example`):
 | `CORS_ALLOW_CREDENTIALS` | `false` | `1`/`true`/`yes`/`on` allow cookies/credentials on cross-origin requests |
 | `CORS_EXPOSE_HEADERS` | unset | Comma-separated response headers exposed to the browser |
 | `CORS_MAX_AGE` | `600` | Seconds browsers may cache the preflight response |
-| `OTEL_ENABLED` | `false` | `1`/`true`/`yes`/`on` enable OpenTelemetry traces and metrics (requires the `otel` extra, i.e. `pip install tavolo-app[otel]`) |
+| `OTEL_ENABLED` | `false` | `1`/`true`/`yes`/`on` enable OpenTelemetry traces and metrics (the Docker image bundles the `otel` extra; non-image installs need `pip install tavolo-app[otel]`) |
 | `OTEL_SERVICE_NAME` | `tavolo` | `service.name` resource attribute of the exported telemetry |
 | `OTEL_EXPORTER_OTLP_ENDPOINT` | unset | Base URL of an OTLP/HTTP collector (e.g. `http://localhost:4318`); unset uses the exporter default |
 | `OTEL_EXPORTER_OTLP_HEADERS` | unset | Comma-separated `key=value` headers sent to the collector (e.g. authentication) |