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/lib/lane-features.js

@@ -99,12 +99,11 @@ function archiveActiveFeature(laneId) {
 
   db.prepare(
     `UPDATE lane_features SET
-       title = ?, branch = ?, pipeline = ?, stage = ?, stage_since = ?, status = ?,
+       branch = ?, pipeline = ?, stage = ?, stage_since = ?, status = ?,
        gate_decision = ?, ci_status = ?, qc_dev = ?, stages = ?, links = ?, notes = ?,
        archived_at = ?, updated_at = ?
      WHERE id = ?`
   ).run(
-    lane.title,
     lane.branch,
     lane.pipeline,
     lane.stage,
@@ -172,7 +171,7 @@ function activateFeature(laneId, rawSlug, options = {}) {
   db.prepare(
     `UPDATE lanes SET
        stage = ?, stage_since = ?, status = ?, gate_decision = ?, ci_status = ?,
-       stages = ?, notes = ?, active_feature_id = ?, updated_at = ?
+       stages = ?, links = ?, notes = ?, active_feature_id = ?, updated_at = ?
      WHERE id = ?`
   ).run(
     target.stage,
@@ -181,6 +180,7 @@ function activateFeature(laneId, rawSlug, options = {}) {
     target.gate_decision,
     target.ci_status,
     JSON.stringify(target.stages || {}),
+    JSON.stringify(target.links || {}),
     target.notes,
     target.id,
     nowIso(),