feat(lanes): let claude and codex lanes coexist at the same cwd

Repo/Adopt mode (POST /api/lanes/ensure) treated lanes.cwd as globally
unique, so adopting a path already driven by one CLI silently ignored a
different tool choice. Uniqueness moves to the composite (cwd, tool):
one directory can now back a claude lane and a codex lane side by side.

- server/db.js: drop the column-level UNIQUE on cwd, migrate existing
  DBs via table rebuild, add idx_lanes_cwd_tool.
- resolveLaneByCwd gains an optional tool filter; hook ingestion always
  pins to "claude" since Codex has no hook mechanism here, so a hook
  event never touches a codex lane sharing the path.
- POST /ensure resolves the existing owner by (cwd, tool) instead of
  cwd alone, so a different tool creates a sibling lane.
- LaneConsolePane's cwd-only lane lookups now also match tool, so a
  shared cwd doesn't attach a run to the wrong sibling lane.

Worktree mode is unaffected (already allocates a unique directory per
lane). docs/LANES.md and CLAUDE.md updated to describe the new
composite uniqueness.

client/src/components/run/LaneConsolePane.tsx

@@ -217,15 +217,22 @@ export function LaneConsolePane({
         // args.laneId — RunSetup always supplies this pane's laneId (a
         // required prop), which would otherwise silently start a run in the
         // wrong lane whenever the user types a cwd different from the one
-        // this pane currently shows.
-        const ownedLane = lanes.find((l) => l.cwd === effectiveCwd);
+        // this pane currently shows. A cwd can now back both a claude lane
+        // and a codex lane, so match this pane's own tool too (laneTool,
+        // which already defaults to "claude" when no lane is selected —
+        // the same default RunSetup renders) — otherwise the wrong sibling
+        // lane could be picked.
+        const ownedLane = lanes.find((l) => l.cwd === effectiveCwd && l.tool === laneTool);
         let targetLaneId: number;
         if (ownedLane) {
           targetLaneId = ownedLane.id;
           if (ownedLane.id !== laneId) onLaneIdChange(ownedLane.id);
         } else {
           try {
-            const ensureResult = await api.lanes.ensure({ cwd: effectiveCwd });
+            const ensureResult = await api.lanes.ensure({
+              cwd: effectiveCwd,
+              tool: laneTool,
+            });
             targetLaneId = ensureResult.lane.id;
             onLaneIdChange(ensureResult.lane.id);
             onLaneCreated(ensureResult.lane);
@@ -287,7 +294,7 @@ export function LaneConsolePane({
         setBusy(null);
       }
     },
-    [busy, t, lanes, laneId, onLaneIdChange, onLaneCreated, attachToRun, refreshList]
+    [busy, t, lanes, laneId, laneTool, onLaneIdChange, onLaneCreated, attachToRun, refreshList]
   );
 
   const onResumeFromHistory = useCallback(
@@ -301,10 +308,13 @@ export function LaneConsolePane({
 
         if (item.cwd) {
           const effectiveCwd = item.cwd;
-          let targetLaneId = lanes.find((l) => l.cwd === effectiveCwd)?.id;
+          // A cwd can now back both a claude lane and a codex lane — match
+          // this history item's own tool, the ground truth for which lane it
+          // belongs to, rather than an arbitrary lane at that cwd.
+          let targetLaneId = lanes.find((l) => l.cwd === effectiveCwd && l.tool === item.tool)?.id;
 
           if (!targetLaneId) {
-            const ensureResult = await api.lanes.ensure({ cwd: effectiveCwd });
+            const ensureResult = await api.lanes.ensure({ cwd: effectiveCwd, tool: item.tool });
             targetLaneId = ensureResult.lane.id;
             onLaneCreated(ensureResult.lane);
           }