feat(lanes,ui): per-lane git surface — Changes panel, VS Code-style diff, branch-aware Add lane, redesigned tooltips (#34, #35)

- Changes card beside lane detail with five modes: Files tree, overview,
  Review (whole diff, per-file collapse), single file, commit history.
- LaneDiffView: unified / side-by-side with independent scroll on both axes
  and mirrored scrollLeft, expand/collapse context, intra-line emphasis.
- Staged-only commit box; git actions (fetch/pull/push/stage/unstage/
  discard/commit/switch/branch-create/branch-delete) guarded in git-ops.js.
- Server: git-diff.js + git-ops.js behind GET /api/lanes/:id/git/* and
  POST /api/lanes/:id/git/:action; gitFacts gains upstream/ahead/behind.
- Add lane: new/existing branch, current branch, worktree list, prefill
  from the git bar's "New lane here"; /api/run/cwds gains a repo kind.
- GlobalTooltip upgrades every native title into a themed anchored bubble;
  chart/info popovers use theme tokens.

client/src/components/workflows/CompactionImpact.tsx

@@ -407,7 +407,7 @@ export function CompactionImpact({ data }: CompactionImpactProps) {
       {/* Hover tooltip (matches the app's other chart tooltips) */}
       {tip && (
         <div
-          className="fixed z-50 pointer-events-none rounded-md border border-[#2a2a4a] bg-[#12121f] px-2.5 py-1.5 text-xs shadow-xl"
+          className="fixed z-50 pointer-events-none rounded-md border border-border bg-surface-2 px-2.5 py-1.5 text-xs shadow-xl"
           style={{
             left: tip.x > window.innerWidth - 220 ? tip.x - 14 : tip.x + 14,
             top: tip.y - 10,

client/src/components/workflows/OrchestrationDAG.tsx

@@ -853,7 +853,7 @@ export function OrchestrationDAG({ data, onNodeClick, selectedNode }: Orchestrat
         ref={tipRef}
         role="tooltip"
         aria-hidden="true"
-        className="fixed z-50 px-3 py-2 bg-[#12121f] border border-[#2a2a4a] rounded-lg shadow-2xl pointer-events-none"
+        className="fixed z-50 px-3 py-2 bg-surface-2 border border-border rounded-lg shadow-2xl pointer-events-none"
         style={{
           display: "none",
           opacity: 0,
@@ -922,10 +922,11 @@ function buildDAGTooltipContent(el: HTMLDivElement, node: DAGNode, t: TFn) {
     row.style.cssText =
       "display:flex;justify-content:space-between;gap:16px;font-size:11px;line-height:1.6";
     const lbl = document.createElement("span");
-    lbl.style.color = "#64748b";
+    lbl.style.color = "rgb(var(--fg-muted))";
     lbl.textContent = label;
     const val = document.createElement("span");
-    val.style.cssText = "color:#cbd5e1;font-weight:500;font-variant-numeric:tabular-nums";
+    val.style.cssText =
+      "color:rgb(var(--fg-primary));font-weight:500;font-variant-numeric:tabular-nums";
     val.textContent = value;
     row.appendChild(lbl);
     row.appendChild(val);
@@ -935,12 +936,12 @@ function buildDAGTooltipContent(el: HTMLDivElement, node: DAGNode, t: TFn) {
 
   const desc = document.createElement("p");
   desc.style.cssText =
-    "font-size:11px;color:#94a3b8;line-height:1.45;border-top:1px solid #2a2a4a;padding-top:8px;margin:0";
+    "font-size:11px;color:rgb(var(--fg-secondary));line-height:1.45;border-top:1px solid rgb(var(--border));padding-top:8px;margin:0";
   desc.textContent = meta.description;
   el.appendChild(desc);
 
   const hint = document.createElement("p");
-  hint.style.cssText = "font-size:10px;color:#64748b;line-height:1.45;margin:6px 0 0";
+  hint.style.cssText = "font-size:10px;color:rgb(var(--fg-muted));line-height:1.45;margin:6px 0 0";
   hint.textContent = t("orchestration.tooltip.tipClickToFilter");
   el.appendChild(hint);
 }

client/src/components/workflows/SessionComplexityScatter.tsx

@@ -115,7 +115,7 @@ function Tooltip({ state }: { state: TooltipState }) {
 
   return (
     <div
-      className="fixed z-50 px-3 py-2 text-xs bg-[#12121f] border border-[#2a2a4a] rounded-lg shadow-xl text-fg-secondary pointer-events-none whitespace-nowrap"
+      className="fixed z-50 px-3 py-2 text-xs bg-surface-2 border border-border rounded-lg shadow-xl text-fg-secondary pointer-events-none whitespace-nowrap"
       style={{
         left: nearRight ? state.x - 12 : state.x + 12,
         top: state.y - 10,
@@ -144,7 +144,7 @@ function Tooltip({ state }: { state: TooltipState }) {
           </span>
         )}
       </div>
-      <div className="mt-1 pt-1 border-t border-[#2a2a4a]">
+      <div className="mt-1 pt-1 border-t border-border">
         <span className="font-medium" style={{ color: statusColor(state.item.status) }}>
           {t(`common:status.${state.item.status}`, { defaultValue: state.item.status })}
         </span>

client/src/components/workflows/WorkflowStats.tsx

@@ -230,10 +230,10 @@ function InfoPopover({ calculationKey, interp, valueDisplay, metricPhraseKey }:
         <div
           ref={popoverRef}
           role="tooltip"
-          className="fixed z-50 p-3 bg-[#12121f] border border-[#2a2a4a] rounded-lg shadow-2xl text-[11px] text-fg-secondary pointer-events-none"
+          className="fixed z-50 p-3 bg-surface-2 border border-border rounded-lg shadow-2xl text-[11px] text-fg-secondary pointer-events-none"
           style={{ left: coords.left, top: coords.top, width: POPOVER_W }}
         >
-          <div className="flex items-baseline gap-2 mb-2 pb-2 border-b border-[#2a2a4a]">
+          <div className="flex items-baseline gap-2 mb-2 pb-2 border-b border-border">
             <span className="text-base font-semibold text-fg-primary tabular-nums">
               {valueDisplay}
             </span>