tutorial: load ./api and ./server as jsx tabs

solid-repl resolves extensionless imports to jsx tabs only, so the .js
helper files in two lessons failed to import. From #1672.

Co-authored-by: Brenley Dueck <brenleydueck@gmail.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0117BoWPLXmEUSKddsQSHkzN

Author: claude

src/tutorials/optimistic-stores.json

@@ -7,8 +7,7 @@
 			},
 			{
 				"name": "api",
-				"content": "const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));\n\n// A pretend server holding the todo list. Saves take 800ms.\nlet serverTodos = [\n  { id: 1, text: 'Learn actions', done: true },\n  { id: 2, text: 'Learn optimistic stores', done: false },\n];\nlet nextId = 3;\nexport const api = {\n  failNext: false,\n  async list() {\n    await sleep(100);\n    return structuredClone(serverTodos);\n  },\n  async toggle(id) {\n    await sleep(800);\n    if (api.failNext) {\n      api.failNext = false;\n      throw new Error('The server rejected that change.');\n    }\n    serverTodos = serverTodos.map((t) => (t.id === id ? { ...t, done: !t.done } : t));\n  },\n  async add(todo) {\n    await sleep(800);\n    serverTodos = [...serverTodos, todo];\n  },\n};\n\nexport const newId = () => nextId++;\n",
-				"type": "js"
+				"content": "const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));\n\n// A pretend server holding the todo list. Saves take 800ms.\nlet serverTodos = [\n  { id: 1, text: 'Learn actions', done: true },\n  { id: 2, text: 'Learn optimistic stores', done: false },\n];\nlet nextId = 3;\nexport const api = {\n  failNext: false,\n  async list() {\n    await sleep(100);\n    return structuredClone(serverTodos);\n  },\n  async toggle(id) {\n    await sleep(800);\n    if (api.failNext) {\n      api.failNext = false;\n      throw new Error('The server rejected that change.');\n    }\n    serverTodos = serverTodos.map((t) => (t.id === id ? { ...t, done: !t.done } : t));\n  },\n  async add(todo) {\n    await sleep(800);\n    serverTodos = [...serverTodos, todo];\n  },\n};\n\nexport const newId = () => nextId++;\n"
 			},
 			{
 				"name": "styles",
@@ -25,8 +24,7 @@
 			},
 			{
 				"name": "api",
-				"content": "const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));\n\n// A pretend server holding the todo list. Saves take 800ms.\nlet serverTodos = [\n  { id: 1, text: 'Learn actions', done: true },\n  { id: 2, text: 'Learn optimistic stores', done: false },\n];\nlet nextId = 3;\nexport const api = {\n  failNext: false,\n  async list() {\n    await sleep(100);\n    return structuredClone(serverTodos);\n  },\n  async toggle(id) {\n    await sleep(800);\n    if (api.failNext) {\n      api.failNext = false;\n      throw new Error('The server rejected that change.');\n    }\n    serverTodos = serverTodos.map((t) => (t.id === id ? { ...t, done: !t.done } : t));\n  },\n  async add(todo) {\n    await sleep(800);\n    serverTodos = [...serverTodos, todo];\n  },\n};\n\nexport const newId = () => nextId++;\n",
-				"type": "js"
+				"content": "const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));\n\n// A pretend server holding the todo list. Saves take 800ms.\nlet serverTodos = [\n  { id: 1, text: 'Learn actions', done: true },\n  { id: 2, text: 'Learn optimistic stores', done: false },\n];\nlet nextId = 3;\nexport const api = {\n  failNext: false,\n  async list() {\n    await sleep(100);\n    return structuredClone(serverTodos);\n  },\n  async toggle(id) {\n    await sleep(800);\n    if (api.failNext) {\n      api.failNext = false;\n      throw new Error('The server rejected that change.');\n    }\n    serverTodos = serverTodos.map((t) => (t.id === id ? { ...t, done: !t.done } : t));\n  },\n  async add(todo) {\n    await sleep(800);\n    serverTodos = [...serverTodos, todo];\n  },\n};\n\nexport const newId = () => nextId++;\n"
 			},
 			{
 				"name": "styles",

src/tutorials/until.json

@@ -7,8 +7,7 @@
 			},
 			{
 				"name": "server",
-				"content": "const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));\n\n// A pretend chat server. Sending returns quickly, but the message only\n// shows up in the live feed a second later, once the server has stored it.\nlet messages = [{ id: 'welcome', text: 'Welcome to the chat!' }];\nconst listeners = new Set();\n\nexport const server = {\n  async send(message) {\n    await sleep(150);\n    setTimeout(() => {\n      messages = [...messages, message];\n      for (const listener of listeners) listener(messages);\n    }, 1000);\n  },\n  // The live feed: yields the full list now, then again after every change.\n  async *watch() {\n    yield messages;\n    while (true) {\n      yield await new Promise((resolve) => {\n        const listener = (list) => {\n          listeners.delete(listener);\n          resolve(list);\n        };\n        listeners.add(listener);\n      });\n    }\n  },\n};\n",
-				"type": "js"
+				"content": "const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));\n\n// A pretend chat server. Sending returns quickly, but the message only\n// shows up in the live feed a second later, once the server has stored it.\nlet messages = [{ id: 'welcome', text: 'Welcome to the chat!' }];\nconst listeners = new Set();\n\nexport const server = {\n  async send(message) {\n    await sleep(150);\n    setTimeout(() => {\n      messages = [...messages, message];\n      for (const listener of listeners) listener(messages);\n    }, 1000);\n  },\n  // The live feed: yields the full list now, then again after every change.\n  async *watch() {\n    yield messages;\n    while (true) {\n      yield await new Promise((resolve) => {\n        const listener = (list) => {\n          listeners.delete(listener);\n          resolve(list);\n        };\n        listeners.add(listener);\n      });\n    }\n  },\n};\n"
 			},
 			{
 				"name": "styles",
@@ -25,8 +24,7 @@
 			},
 			{
 				"name": "server",
-				"content": "const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));\n\n// A pretend chat server. Sending returns quickly, but the message only\n// shows up in the live feed a second later, once the server has stored it.\nlet messages = [{ id: 'welcome', text: 'Welcome to the chat!' }];\nconst listeners = new Set();\n\nexport const server = {\n  async send(message) {\n    await sleep(150);\n    setTimeout(() => {\n      messages = [...messages, message];\n      for (const listener of listeners) listener(messages);\n    }, 1000);\n  },\n  // The live feed: yields the full list now, then again after every change.\n  async *watch() {\n    yield messages;\n    while (true) {\n      yield await new Promise((resolve) => {\n        const listener = (list) => {\n          listeners.delete(listener);\n          resolve(list);\n        };\n        listeners.add(listener);\n      });\n    }\n  },\n};\n",
-				"type": "js"
+				"content": "const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));\n\n// A pretend chat server. Sending returns quickly, but the message only\n// shows up in the live feed a second later, once the server has stored it.\nlet messages = [{ id: 'welcome', text: 'Welcome to the chat!' }];\nconst listeners = new Set();\n\nexport const server = {\n  async send(message) {\n    await sleep(150);\n    setTimeout(() => {\n      messages = [...messages, message];\n      for (const listener of listeners) listener(messages);\n    }, 1000);\n  },\n  // The live feed: yields the full list now, then again after every change.\n  async *watch() {\n    yield messages;\n    while (true) {\n      yield await new Promise((resolve) => {\n        const listener = (list) => {\n          listeners.delete(listener);\n          resolve(list);\n        };\n        listeners.add(listener);\n      });\n    }\n  },\n};\n"
 			},
 			{
 				"name": "styles",