feat(desktop): add file attachments and native chat window

- Add file upload support in chat (PDF, images, txt, docs, xlsx)
  - Limited to 10MB max file size
  - Only allowed extensions for security
- Use native Windows decorations for chat window
- Remove ChatFloatingWidget (replaced by native window)
- Simplify chat event listeners (window managed by Rust)
- Fix typo "sessao" -> "sessão"

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/app/api/machines/chat/upload/route.ts

@@ -0,0 +1,73 @@
+import { z } from "zod"
+
+import { api } from "@/convex/_generated/api"
+import { createCorsPreflight, jsonWithCors } from "@/server/cors"
+import { createConvexClient, ConvexConfigurationError } from "@/server/convex-client"
+
+const uploadUrlSchema = z.object({
+  machineToken: z.string().min(1),
+  fileName: z.string().min(1),
+  fileType: z.string().min(1),
+  fileSize: z.number().positive(),
+})
+
+const CORS_METHODS = "POST, OPTIONS"
+
+export async function OPTIONS(request: Request) {
+  return createCorsPreflight(request.headers.get("origin"), CORS_METHODS)
+}
+
+// POST /api/machines/chat/upload
+// Gera URL de upload para anexos do chat
+export async function POST(request: Request) {
+  const origin = request.headers.get("origin")
+
+  let client
+  try {
+    client = createConvexClient()
+  } catch (error) {
+    if (error instanceof ConvexConfigurationError) {
+      return jsonWithCors({ error: error.message }, 500, origin, CORS_METHODS)
+    }
+    throw error
+  }
+
+  let raw
+  try {
+    raw = await request.json()
+  } catch {
+    return jsonWithCors({ error: "JSON invalido" }, 400, origin, CORS_METHODS)
+  }
+
+  let payload
+  try {
+    payload = uploadUrlSchema.parse(raw)
+  } catch (error) {
+    return jsonWithCors(
+      { error: "Payload invalido", details: error instanceof Error ? error.message : String(error) },
+      400,
+      origin,
+      CORS_METHODS
+    )
+  }
+
+  try {
+    const result = await client.action(api.liveChat.generateMachineUploadUrl, {
+      machineToken: payload.machineToken,
+      fileName: payload.fileName,
+      fileType: payload.fileType,
+      fileSize: payload.fileSize,
+    })
+    return jsonWithCors(result, 200, origin, CORS_METHODS)
+  } catch (error) {
+    console.error("[machines.chat.upload] Falha ao gerar URL de upload", error)
+    const details = error instanceof Error ? error.message : String(error)
+
+    // Se for erro de validacao, retornar 400
+    if (details.includes("não permitido") || details.includes("muito grande") || details.includes("inválido")) {
+      return jsonWithCors({ error: details }, 400, origin, CORS_METHODS)
+    }
+
+    return jsonWithCors({ error: "Falha ao gerar URL de upload", details }, 500, origin, CORS_METHODS)
+  }
+}