fix(insights): promote coach-rail labels to semantic h3 headings

The history and sources rails mount inline next to the message thread
on lg+ / xl+ viewports, where no SheetTitle wrapper covers them.
Both rails previously rendered their section labels as <span> with
uppercase styling, so the drawer's semantic outline disappeared above
the message thread on desktop. Screen-reader users navigating by
heading skipped straight from the drawer's <h2> title to the
message-thread region with no intermediate landmark.

Promote both labels to <h3> while keeping the existing visual
treatment intact. The mobile rail-tray (Sheet-wrapped) still surfaces
its SheetTitle <h2>, so the rail's own <h3> simply nests below it on
small screens. The desktop layout now carries a coherent h2 (drawer)
> h3 (rail) hierarchy.

Regression tests assert that each rail renders its label inside a
real <h3> element so the semantic outline cannot silently drop again.

src/components/insights/coach-panel/__tests__/history-rail.test.tsx

@@ -66,6 +66,21 @@ describe("<HistoryRail>", () => {
     expect(html).toContain("Conversations");
   });
 
+  it("renders the rail label as a real `<h3>` heading (v1.4.33)", () => {
+    // The rail mounts inline on `lg+` desktop where no `SheetTitle`
+    // wrapper covers it. Without a real heading element the drawer
+    // lost its semantic outline above the message thread — fixed in
+    // v1.4.33 by promoting the rail label to `<h3>`.
+    const client = makeClientWithConversations(samplePage);
+    const html = render(
+      <HistoryRail activeId={null} onSelect={() => {}} />,
+      client,
+    );
+    expect(html).toMatch(
+      /<h3[^>]*data-slot="coach-history-rail-heading"[^>]*>[\s\S]*Conversations[\s\S]*<\/h3>/,
+    );
+  });
+
   it("renders one row per conversation", () => {
     const client = makeClientWithConversations(samplePage);
     const html = render(

src/components/insights/coach-panel/__tests__/sources-rail.test.tsx

@@ -17,6 +17,17 @@ describe("<SourcesRail>", () => {
     expect(html).toContain("What I can see");
   });
 
+  it("renders the rail label as a real `<h3>` heading (v1.4.33)", () => {
+    // The rail mounts inline on `xl+` desktop where no `SheetTitle`
+    // wrapper covers it. Promoting the label to `<h3>` restores the
+    // drawer's semantic outline so screen-reader users can navigate
+    // by heading.
+    const html = render(<SourcesRail />);
+    expect(html).toMatch(
+      /<h3[^>]*data-slot="coach-sources-rail-heading"[^>]*>[\s\S]*What I can see[\s\S]*<\/h3>/,
+    );
+  });
+
   it("lists exactly five rows (BP, weight, pulse, mood, compliance)", () => {
     const html = render(<SourcesRail />);
     const rows = html.match(/data-slot="coach-sources-row"/g) ?? [];

src/components/insights/coach-panel/history-rail.tsx

@@ -69,15 +69,23 @@ export function HistoryRail({
       data-slot="coach-history-rail"
       className={cn("flex h-full min-h-0 flex-col gap-2 p-3", className)}
     >
-      <div className="flex items-center gap-1.5 px-1">
+      {/* v1.4.33 — promote the rail label from a `<span>` to a real
+          `<h3>` so the drawer carries a semantic outline on desktop
+          where the rail is mounted inline (no `SheetTitle` wrapper).
+          The mobile rail-tray still wraps the rail inside its own
+          `SheetTitle`, so screen-reader users hear the section twice
+          when the tray is open — that's intentional Radix behaviour
+          (the rail still has to stand alone on desktop). */}
+      <h3
+        data-slot="coach-history-rail-heading"
+        className="text-muted-foreground flex items-center gap-1.5 px-1 text-[11px] font-medium tracking-wide uppercase"
+      >
         <MessagesSquare
           className="text-muted-foreground size-3.5"
           aria-hidden="true"
         />
-        <span className="text-muted-foreground text-[11px] font-medium tracking-wide uppercase">
-          {t("insights.coach.historyTitle")}
-        </span>
-      </div>
+        {t("insights.coach.historyTitle")}
+      </h3>
       <div className="relative">
         <Search
           aria-hidden="true"

src/components/insights/coach-panel/sources-rail.tsx

@@ -172,12 +172,20 @@ export function SourcesRail({
       data-slot="coach-sources-rail"
       className={cn("flex h-full min-h-0 flex-col gap-3 p-3", className)}
     >
-      <div className="flex items-center gap-1.5 px-1">
+      {/* v1.4.33 — promote the rail label from a `<span>` to a real
+          `<h3>` so the rail carries a semantic outline on desktop
+          where it mounts inline next to the message thread. The
+          mobile rail-tray wraps the rail inside its own `SheetTitle`
+          (an `<h2>`), so the rail's own `<h3>` simply nests beneath
+          it — the heading hierarchy stays consistent across
+          viewports. */}
+      <h3
+        data-slot="coach-sources-rail-heading"
+        className="text-muted-foreground flex items-center gap-1.5 px-1 text-[11px] font-medium tracking-wide uppercase"
+      >
         <Eye className="text-muted-foreground size-3.5" aria-hidden="true" />
-        <span className="text-muted-foreground text-[11px] font-medium tracking-wide uppercase">
-          {t("insights.coach.sourcesTitle")}
-        </span>
-      </div>
+        {t("insights.coach.sourcesTitle")}
+      </h3>
 
       {/* Window selector — every row below is filtered to the picked
           window when the next Coach message goes out. 36px touch