feat(lanes): add ccam skills install (E, F3b)

Copies .claude/skills/ship-feature-lane/ into ~/.claude/skills/, so
/ship-feature-lane is discoverable from a session running inside any
lane's own working directory — not just inside this repo, which is
where it lived until now (Claude Code only auto-discovers .claude/
directories from the repo that owns them). Pure filesystem action,
same self-location REPO_ROOT already gives lanes profile init.

bin/ccam.js

@@ -1520,6 +1520,27 @@ async function cmdLanesAdd(args) {
   console.log(`${c.green("✔")} Created lane #${lane.id}: ${lane.title}`);
 }
 
+/**
+ * `ccam skills install` — copy this checkout's `.claude/skills/ship-feature-lane/`
+ * into `~/.claude/skills/ship-feature-lane/`, so `/ship-feature-lane` is
+ * discoverable from a session running inside any lane's own working
+ * directory, not just inside this repo. Pure filesystem action; does not
+ * talk to the dashboard server at all. Reinstall, not merge — overwrites an
+ * existing global copy with the current one.
+ */
+function cmdSkillsInstall() {
+  const src = path.join(REPO_ROOT, ".claude", "skills", "ship-feature-lane");
+  if (!fs.existsSync(src)) {
+    console.error(`✖ not found: ${src}`);
+    process.exitCode = 1;
+    return;
+  }
+  const dest = path.join(require("node:os").homedir(), ".claude", "skills", "ship-feature-lane");
+  fs.mkdirSync(path.dirname(dest), { recursive: true });
+  fs.cpSync(src, dest, { recursive: true, force: true });
+  console.log(`${c.green("✔")} installed ship-feature-lane skill -> ${dest}`);
+}
+
 /**
  * `ccam lanes profile init <repo>` — detect a Node.js project and scaffold
  * `.ccam/profile/`. Pure filesystem action against the SOURCE repo; does not
@@ -2412,6 +2433,11 @@ const COMMAND_GROUPS = [
         "<name> [<id>]",
         "Check whether a named integration (tracker, dev_qc, ci_wait) is on for this lane — exit 0/1",
       ],
+      [
+        "skills install",
+        "",
+        "Install .claude/skills/ship-feature-lane/ into ~/.claude/skills/ so /ship-feature-lane works from any lane",
+      ],
       [
         "lock status|acquire|release",
         "[<name>] [--holder X] [--timeout N]",
@@ -3240,6 +3266,12 @@ async function runCommand(argv) {
         return cmdLanesIntegration(rest.slice(1));
       }
       return cmdLanes();
+    case "skills": {
+      if (rest[0] === "install") return cmdSkillsInstall();
+      console.error("usage: ccam skills install");
+      process.exitCode = 1;
+      return;
+    }
     case "lock": {
       const sub = rest[0];
       if (sub === "status") return cmdLockStatus(rest.slice(1));