Fix page editing: use Ghost /pages/ API for pages, not /posts/

Ghost has separate /posts/ and /pages/ endpoints. All admin functions
(get_post_for_edit, update_post, update_post_settings, sync) were
hardcoded to /posts/, causing 404s when editing pages. Now checks
is_page from post_data and uses the correct endpoint.

Also uses sync_single_page (not sync_single_post) after page saves
to prevent IntegrityError from mismatched fetch/upsert paths.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

bp/blog/ghost/ghost_posts.py

@@ -30,10 +30,11 @@ def _check(resp: httpx.Response) -> None:
     resp.raise_for_status()
 
 
-async def get_post_for_edit(ghost_id: str) -> dict | None:
-    """Fetch a single post by Ghost ID, including lexical source."""
+async def get_post_for_edit(ghost_id: str, *, is_page: bool = False) -> dict | None:
+    """Fetch a single post/page by Ghost ID, including lexical source."""
+    resource = "pages" if is_page else "posts"
     url = (
-        f"{GHOST_ADMIN_API_URL}/posts/{ghost_id}/"
+        f"{GHOST_ADMIN_API_URL}/{resource}/{ghost_id}/"
         "?formats=lexical,html,mobiledoc&include=newsletters"
     )
     async with httpx.AsyncClient(timeout=30) as client:
@@ -41,7 +42,7 @@ async def get_post_for_edit(ghost_id: str) -> dict | None:
         if resp.status_code == 404:
             return None
         _check(resp)
-    return resp.json()["posts"][0]
+    return resp.json()[resource][0]
 
 
 async def create_post(
@@ -114,6 +115,7 @@ async def update_post(
     newsletter_slug: str | None = None,
     email_segment: str | None = None,
     email_only: bool | None = None,
+    is_page: bool = False,
 ) -> dict:
     """Update an existing Ghost post.  Returns the updated post dict.
 
@@ -141,9 +143,10 @@ async def update_post(
         post_body["status"] = status
     if email_only:
         post_body["email_only"] = True
-    payload = {"posts": [post_body]}
+    resource = "pages" if is_page else "posts"
+    payload = {resource: [post_body]}
 
-    url = f"{GHOST_ADMIN_API_URL}/posts/{ghost_id}/"
+    url = f"{GHOST_ADMIN_API_URL}/{resource}/{ghost_id}/"
     if newsletter_slug:
         url += f"?newsletter={newsletter_slug}"
         if email_segment:
@@ -151,7 +154,7 @@ async def update_post(
     async with httpx.AsyncClient(timeout=30) as client:
         resp = await client.put(url, json=payload, headers=_auth_header())
         _check(resp)
-    return resp.json()["posts"][0]
+    return resp.json()[resource][0]
 
 
 _SETTINGS_FIELDS = (
@@ -178,22 +181,24 @@ _SETTINGS_FIELDS = (
 async def update_post_settings(
     ghost_id: str,
     updated_at: str,
+    is_page: bool = False,
     **kwargs,
 ) -> dict:
-    """Update Ghost post settings (slug, tags, SEO, social, etc.).
+    """Update Ghost post/page settings (slug, tags, SEO, social, etc.).
 
     Only non-None keyword args are included in the PUT payload.
     Accepts any key from ``_SETTINGS_FIELDS``.
     """
+    resource = "pages" if is_page else "posts"
     post_body: dict = {"updated_at": updated_at}
     for key in _SETTINGS_FIELDS:
         val = kwargs.get(key)
         if val is not None:
             post_body[key] = val
 
-    payload = {"posts": [post_body]}
-    url = f"{GHOST_ADMIN_API_URL}/posts/{ghost_id}/"
+    payload = {resource: [post_body]}
+    url = f"{GHOST_ADMIN_API_URL}/{resource}/{ghost_id}/"
     async with httpx.AsyncClient(timeout=30) as client:
         resp = await client.put(url, json=payload, headers=_auth_header())
         _check(resp)
-    return resp.json()["posts"][0]
+    return resp.json()[resource][0]