fix(lanes): stop archive/activate from clobbering feature title and links

archiveActiveFeature was overwriting a feature's own title with the
LIVE lane's title on every clear/switch — a --title set on activation
silently disappeared. activateFeature restored stage/status/gate/CI/
stages/notes onto the live lane when switching back to a past feature,
but never links, so they vanished on reactivation. Both are fixed, with
a regression test for each (full activate/archive/reactivate round trip
for links).

Also fixes server/routes/lanes.js: the doc comment explaining GET
/:id/git's rationale had been left sitting above the newly-inserted
/:id/features routes instead of its own route.

docs/API.md's Lane features section described fields and behavior that
don't exist in the real routes (an "active" boolean, a POST response
containing "archivedPrevious", a "409 ESTALE" concurrency response) —
rewritten to match the actual request/response shapes exactly.

server/__tests__/lane-features.test.js

@@ -112,6 +112,26 @@ describe("activateFeature / archiveActiveFeature", () => {
     const { feature } = features.activateFeature(lane.id, "feat/Weird Input/");
     assert.equal(feature.slug, "Weird-Input");
   });
+
+  it("a feature's own title survives being archived (never clobbered by the lane's title)", () => {
+    const lane = makeLane();
+    features.activateFeature(lane.id, "one", { title: "Custom title" });
+    features.activateFeature(lane.id, "two"); // archives "one"
+    assert.equal(features.getFeature(lane.id, "one").title, "Custom title");
+  });
+
+  it("links survive a full activate -> archive -> reactivate round trip", () => {
+    const lane = makeLane();
+    features.activateFeature(lane.id, "one");
+    lanesLib.updateLane(lane.id, { links: { pr: "https://example.com/pr/1" } });
+    features.activateFeature(lane.id, "two"); // archives "one" with its links
+
+    const archived = features.getFeature(lane.id, "one");
+    assert.deepEqual(archived.links, { pr: "https://example.com/pr/1" });
+
+    const { lane: reactivated } = features.activateFeature(lane.id, "one");
+    assert.deepEqual(reactivated.links, { pr: "https://example.com/pr/1" });
+  });
 });
 
 describe("listFeatures / getFeature", () => {