fix(git,macos,runs): close the review findings on #22, #34 and #38

- validateRemoteUrl checks the literal scheme prefix git will receive and
  refuses %/backslash in the authority (WHATWG normalises https:/host and
  percent-escapes that git reads differently); route test for EBADURL.
- Parent-session scrub also drops AI_AGENT, and GIT_EDITOR when it is
  Claude Code's `true`.
- canonicalCwd resolves a not-yet-existing path through its deepest
  existing ancestor, so a symlinked parent still yields one lane.
- Note the clock-step ceiling on liveServers' boot-time filter.
- Docs/header wording: the Active runs count is lane-scoped.

server/__tests__/lanes-api.test.js

@@ -921,6 +921,13 @@ describe("the lane git surface: changes, branches, actions (issue #34)", () => {
     assert.equal(bogus.body.error.code, "EBADACTION");
   });
 
+  it("400s a publish to a url that is not https, ssh or scp-like", async () => {
+    const r = await request("POST", `/api/lanes/${laneId}/git/publish`, { url: "file:///tmp/x" });
+    assert.equal(r.status, 400);
+    assert.equal(r.body.error.code, "EBADURL");
+    assert.equal(g(dir, "remote").trim(), "");
+  });
+
   it("reads the log, one commit's diff, a whole file, the path list and the tree", async () => {
     const log = await request("GET", `/api/lanes/${laneId}/git/log?limit=5`);
     assert.equal(log.status, 200);
@@ -1442,6 +1449,23 @@ describe("/api/lanes tool tests", () => {
     assert.equal(second.body.lane.id, first.body.lane.id);
   });
 
+  it("POST /api/lanes/ensure resolves a symlinked path, existing or not, to one lane", async () => {
+    const real = fs.mkdtempSync(path.join(os.tmpdir(), "lane-real-"));
+    const link = `${real}-link`;
+    fs.symlinkSync(real, link);
+    try {
+      for (const sub of ["", "/not-yet"]) {
+        const first = await request("POST", "/api/lanes/ensure", { cwd: real + sub });
+        const second = await request("POST", "/api/lanes/ensure", { cwd: link + sub });
+        assert.equal(second.body.created, false, sub);
+        assert.equal(second.body.lane.id, first.body.lane.id, sub);
+      }
+    } finally {
+      fs.rmSync(link);
+      fs.rmSync(real, { recursive: true });
+    }
+  });
+
   it("POST /api/lanes/ensure re-ensuring with the same tool is a no-op", async () => {
     const first = await request("POST", "/api/lanes/ensure", {
       cwd: "/tmp/same-tool-lane",