feat(paseo): add Go, Python, shell tooling, hostname and timezone

Go 1.26.8 from the official tarball and Python 3.12 via uv, since Debian
12 carries 1.19 and 3.11. Both land outside $HOME, which the paseo-home
volume would otherwise mask.

Hostname and timezone come from the environment rather than being fixed in
the compose file. Paseo uses the container hostname as the host label in
its web UI, so without one the UI shows a random container ID.

paseo/.env.example

@@ -16,3 +16,10 @@ PASEO_HOSTNAMES=
 # ws://...:6767 from an HTTPS page -- which the browser blocks.
 # `uniquelocal` covers the private ranges Docker bridge networks use.
 PASEO_TRUSTED_PROXIES=uniquelocal
+
+# Container hostname. Paseo shows it as the host label in the web UI, so
+# without it you get a random container ID.
+PASEO_LABEL=paseo
+
+# Timezone for logs and agent shells.
+TZ=Asia/Ho_Chi_Minh