Migrate the backend from pip to uv

Replace requirements.txt with a uv workspace and lockfile, install the five tavolo packages from packages/* in development and non-editable in the image, and build the Docker image with uv. Move dev tools to a PEP 735 dependency group and refresh the locked dependency versions.

server/packages/tavolo-app/README.md

@@ -29,7 +29,7 @@ The deployable tavolo application: the composition root wiring
 ## Development (from `packages/tavolo-app/`)
 
 ```sh
-.venv/bin/python -m mypy --namespace-packages --explicit-package-bases \
+uv run mypy --namespace-packages --explicit-package-bases \
   src/tavolo/app.py \
   src/tavolo/config.py \
   src/tavolo/telemetry.py \

server/packages/tavolo-app/pyproject.toml

@@ -31,10 +31,6 @@ dependencies = [
 ]
 
 [project.optional-dependencies]
-dev = [
-    "mypy",
-    "httpx-ws",
-]
 otel = [
     "kaya-otel>=0.0.7",
     "opentelemetry-instrumentation-asyncpg>=0.66b0",
@@ -42,6 +38,12 @@ otel = [
     "opentelemetry-instrumentation-system-metrics>=0.66b0",
 ]
 
+[dependency-groups]
+dev = [
+    "mypy",
+    "httpx-ws",
+]
+
 [tool.setuptools.packages.find]
 where = ["src"]
 namespaces = true