fix(nix): put claude on the cc-ci-loops service PATH so loops start on boot

The service path lacked /home/loops/.local/bin, so launch.py preflight's
which(claude) failed on every boot and the loops never auto-started
(they were restarted by hand). Set CLAUDE_BIN to the standalone CLI's
absolute path and prepend the dir to PATH so the tmux server every agent
session inherits resolves bare claude.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

nix/hosts/cc-ci-orchestrator-hetzner/configuration.nix

@@ -169,9 +169,15 @@ SSHCFG
       # Append one line to REBOOTS.md per genuine reboot (boot_id-gated; not on manual restart).
       ExecStartPre = "${pkgs.bash}/bin/bash /srv/cc-ci/cc-ci-plan/reboot-log.sh";
     };
-    environment = { RESUME_PHASE = "1"; HOME = "/home/loops"; };
+    # CLAUDE_BIN points at the standalone CLI installed by claude-install.service; the loops
+    # backend defaults to claude (persisted in .loop-backend). Without this, launch.py's preflight
+    # `which(claude)` fails because the systemd `path` below has no /home/loops/.local/bin.
+    environment = { RESUME_PHASE = "1"; HOME = "/home/loops"; CLAUDE_BIN = "/home/loops/.local/bin/claude"; };
     path = [ pkgs.bash pkgs.tmux pkgs.git pkgs.python3 pkgs.openssh pkgs.nettools ];
     script = ''
+      # Put the standalone claude/opencode binaries on PATH. On a cold boot this is the env the
+      # tmux server (and thus every agent session) inherits, so bare `claude` resolves everywhere.
+      export PATH="/home/loops/.local/bin:$PATH"
       [ -x /srv/cc-ci/cc-ci-plan/launch.sh ] && /srv/cc-ci/cc-ci-plan/launch.sh start || \
         echo "workspace not staged yet — skipping loop start"
     '';