fix(web): parse markdown responses as text in WebPlatformAdapter.fetchRemoteConfig

Importing a skill from the cloud market failed with
'SyntaxError: No number after minus sign in JSON at position 1 (line 1 column 2)'
because the WebPlatformAdapter hard-coded res.json() for every response, while
the same IPC handler on Electron already routes by Content-Type / .json suffix
(see apps/desktop/main/ipc/window.ts: '支持 JSON 和纯文本/Markdown').

The Electron path handled skill bodies (.md) correctly; the Web path only
worked for the catalog (skill.json). Aligning the Web adapter with the same
Content-Type / .json-suffix rule fixes both fetchCloudCatalog and
importFromCloud at once, with no new abstraction.

src/services/platform/web.test.ts

@@ -71,4 +71,35 @@ describe('WebPlatformAdapter', () => {
       globalThis.fetch = originalFetch
     }
   })
+
+  it('parses markdown skill bodies as text instead of JSON', async () => {
+    // Regression: importing a skill from the cloud market failed with
+    // "SyntaxError: No number after minus sign in JSON..." because
+    // fetchRemoteConfig hard-coded res.json() for every response.
+    const originalFetch = globalThis.fetch
+    const md = `---\nid: skill_md\nname: Markdown Skill\ndescription: desc\n---\nbody text`
+    globalThis.fetch = (() =>
+      Promise.resolve(new Response(md, { headers: { 'content-type': 'text/markdown' } }))) as typeof fetch
+
+    try {
+      const result = await new WebPlatformAdapter().fetchRemoteConfig('https://example.com/skills/skill_md.md')
+      assert.equal(result.success, true)
+      assert.equal(result.data, md)
+    } finally {
+      globalThis.fetch = originalFetch
+    }
+  })
+
+  it('parses .json URLs as JSON even without an application/json content-type', async () => {
+    const originalFetch = globalThis.fetch
+    globalThis.fetch = (() =>
+      Promise.resolve(new Response('[1,2,3]', { headers: { 'content-type': 'text/plain' } }))) as typeof fetch
+
+    try {
+      const result = await new WebPlatformAdapter().fetchRemoteConfig('https://example.com/cn/skill.json')
+      assert.deepEqual(result.data, [1, 2, 3])
+    } finally {
+      globalThis.fetch = originalFetch
+    }
+  })
 })

src/services/platform/web.ts

@@ -25,7 +25,9 @@ export class WebPlatformAdapter implements PlatformAdapter {
     try {
       const res = await fetch(url)
       if (!res.ok) return { success: false, error: `HTTP ${res.status}` }
-      const data = await res.json()
+      const contentType = res.headers.get('content-type') || ''
+      const isJson = contentType.includes('application/json') || url.split('?')[0].endsWith('.json')
+      const data = isJson ? await res.json() : await res.text()
       return { success: true, data }
     } catch (e) {
       return { success: false, error: String(e) }