Add ssh-agent service and ssh config

Add a systemd user service to start the ssh-agent and add an ssh
config to automatically add ssh identities to the agent when they
are used (otherwise we have to add them manually). I will see how
this works out.

See: https://wiki.archlinux.org/title/SSH_keys#SSH_agents

config.yaml

@@ -63,6 +63,12 @@ dotfiles:
   d_local_bin:
     src: local/bin
     dst: ~/.local/bin
+  f_ssh_config:
+    src: ssh/config
+    dst: ~/.ssh/config
+  f_ssh-agent.service:
+    src: config/systemd/user/ssh-agent.service
+    dst: ~/.config/systemd/user/ssh-agent.service
 profiles:
   everywhere:
     dotfiles:
@@ -90,6 +96,7 @@ profiles:
     - f_pam_environment
     - f_xdg_desktop_portal_wlr_config
     - d_local_bin
+    - f_ssh-agent.service
   knafeh:
     dotfiles:
     - d_vim
@@ -111,3 +118,4 @@ profiles:
     - f_xdg_desktop_portal_wlr_config
     - f_geoclue-agent.service
     - d_local_bin
+    - f_ssh-agent.service