Unify inline-editable field styling app-wide

Device display name, session title, and session description editors
now share one style: underline is invisible until hover/focus (then
primary), the caret is primary while editing, and text keeps its own
default color at all times instead of shifting on focus.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WzyfRyA7h5rs5SCAahLAWd

components/devices/DevicesTable.tsx

@@ -3,7 +3,6 @@
 import { useEffect, useRef, useState } from "react";
 import { useRouter } from "next/navigation";
 import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table";
-import { Input } from "@/components/ui/input";
 import { Check, Loader2 } from "lucide-react";
 import { toast } from "sonner";
 import { cn } from "@/lib/utils";
@@ -55,23 +54,23 @@ function DeviceNameCell({ device }: { device: DeviceRow }) {
   }, [status]);
 
   return (
-    <div className="relative w-48">
-      <Input
+    <div className="flex items-center gap-2">
+      <input
         value={value}
         onChange={(e) => setValue(e.target.value)}
-        className="h-8 pr-8"
         aria-label="Device display name"
+        className="max-w-48 min-w-0 border-b-2 border-transparent bg-transparent text-sm font-medium text-foreground caret-primary outline-none transition-colors placeholder:text-muted-foreground/70 hover:border-b-primary focus:border-b-primary [field-sizing:content]"
       />
-      <div className="pointer-events-none absolute inset-y-0 right-2 flex w-3.5 items-center justify-center">
+      <div className="relative flex size-4 shrink-0 items-center justify-center">
         <Loader2
           className={cn(
-            "absolute size-3.5 animate-spin text-muted-foreground transition-opacity",
+            "absolute size-4 animate-spin text-muted-foreground transition-opacity",
             status === "saving" ? "opacity-100" : "opacity-0",
           )}
         />
         <Check
           className={cn(
-            "absolute size-3.5 text-primary transition-opacity",
+            "absolute size-4 text-primary transition-opacity",
             status === "saved" ? "opacity-100" : "opacity-0",
           )}
         />