feat(nix): ship the pr-daemon, hourlog and week-review units

The units ran from nixos-config while the scripts they execute live
here, so a fix like KillMode had to be made in the repo that does not
contain the daemon. They are defined here now and each machine opts in
with programs.agentSkills.<name>.enable, which keeps the property that
nothing starts a session unless a host asks for it.

ExecStart still points at the checkout, not the store: an edit should
take effect on restart rather than needing a flake bump.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

README.md

@@ -45,6 +45,19 @@ imports = [ inputs.agent-skills.homeModules.default ];
 
 `recursive = true` links files individually, so machine-local skills can coexist in the same dir. `nixos-rebuild switch` to apply/update.
 
+The module also carries the user units — `pr-daemon`, `hourlog`, `week-review` — so each lives next to the script it runs. All three are off by default, because every one of them starts an agent session and a second machine enabling them would run the same job twice:
+
+```nix
+programs.agentSkills = {
+  machine = "yolo";
+  prDaemon.enable = true;
+  hourlog.enable = true;
+  weekReview.enable = true;
+};
+```
+
+`repoPath` (default `%h/tea/agent-skills`) is what the units execute from. Deliberately a checkout rather than a store path: the daemon and the scripts change far more often than the flake input is bumped, so a restart is enough to pick up an edit. The `systemd/` unit files stay for non-Nix machines, where `link.sh` installs them.
+
 ## Shared machine, many sessions
 
 Several autonomous runs share one box. `skills/linear-common/scripts/gate.sh` is a machine-wide semaphore for heavy commands (full test suites, whole-project builds): bounded slots, memory + CPU cap via a systemd user scope, pinned build/test parallelism. Skills run scoped checks in the inner loop and put only the once-per-push full suite through the gate; exit 75 means it never ran and CI takes over. Policy lives in `linear-common/COMMON.md` under "Local verification budget".