Unify post admin nav across all services

Move post admin header into shared/sexp/helpers.py so blog, cart,
events, and market all render the same admin row with identical nav:
calendars | markets | payments | entries | data | edit | settings.

All links are external (cross-service). The selected item shows
highlighted on the right and as white text next to "admin" on the left.

- blog: delegates to shared helper, removes blog-specific nav builder
- cart: delegates to shared helper for payments admin
- events: adds shared admin row (selected=calendars) to calendar admin
- market: adds /<slug>/admin/ route + page_admin blueprint, delegates
  to shared helper (selected=markets). Fixes 404 on page-level admin.

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

market/app.py

@@ -11,7 +11,7 @@ from sqlalchemy import select
 from shared.infrastructure.factory import create_base_app
 from shared.config import config
 
-from bp import register_market_bp, register_all_markets, register_page_markets, register_fragments, register_actions, register_data
+from bp import register_market_bp, register_all_markets, register_page_markets, register_page_admin, register_fragments, register_actions, register_data
 
 
 async def market_context() -> dict:
@@ -111,6 +111,12 @@ def create_app() -> "Quart":
         url_prefix="/<slug>",
     )
 
+    # Page admin: /<slug>/admin/ — post-level admin for markets
+    app.register_blueprint(
+        register_page_admin(),
+        url_prefix="/<slug>/admin",
+    )
+
     # Market blueprint nested under post slug: /<page_slug>/<market_slug>/
     app.register_blueprint(
         register_market_bp(

market/bp/__init__.py

@@ -2,6 +2,7 @@ from .market.routes import register as register_market_bp
 from .product.routes import register as register_product
 from .all_markets.routes import register as register_all_markets
 from .page_markets.routes import register as register_page_markets
+from .page_admin.routes import register as register_page_admin
 from .fragments import register_fragments
 from .actions import register_actions
 from .data import register_data

market/bp/page_admin/routes.py

@@ -0,0 +1,25 @@
+from __future__ import annotations
+
+from quart import make_response, Blueprint
+
+from shared.browser.app.authz import require_admin
+from shared.browser.app.utils.htmx import is_htmx_request
+
+
+def register():
+    bp = Blueprint("page_admin", __name__)
+
+    @bp.get("/")
+    @require_admin
+    async def admin(**kwargs):
+        from shared.sexp.page import get_template_context
+        from sexp.sexp_components import render_page_admin_page, render_page_admin_oob
+
+        tctx = await get_template_context()
+        if not is_htmx_request():
+            html = await render_page_admin_page(tctx)
+        else:
+            html = await render_page_admin_oob(tctx)
+        return await make_response(html)
+
+    return bp

market/sexp/sexp_components.py

@@ -15,6 +15,7 @@ from shared.sexp.jinja_bridge import render, load_service_components
 from shared.sexp.helpers import (
     call_url, get_asset_url, root_header_html,
     post_header_html as _post_header_html,
+    post_admin_header_html,
     oob_header_html as _oob_header_html,
     search_mobile_html, search_desktop_html,
     full_page, oob_page,
@@ -1420,7 +1421,7 @@ async def render_market_admin_page(ctx: dict) -> str:
     content = "market admin"
 
     hdr = root_header_html(ctx)
-    child = _post_header_html(ctx) + _market_header_html(ctx) + _market_admin_header_html(ctx)
+    child = _post_header_html(ctx) + _market_header_html(ctx) + _market_admin_header_html(ctx, selected="markets")
     hdr += render("header-child", inner_html=child)
     return full_page(ctx, header_rows_html=hdr, content_html=content)
 
@@ -1431,21 +1432,37 @@ async def render_market_admin_oob(ctx: dict) -> str:
 
     oobs = _market_header_html(ctx, oob=True)
     oobs += _oob_header_html("market-header-child", "market-admin-header-child",
-                              _market_admin_header_html(ctx))
+                              _market_admin_header_html(ctx, selected="markets"))
     return oob_page(ctx, oobs_html=oobs, content_html=content)
 
 
-def _market_admin_header_html(ctx: dict, *, oob: bool = False) -> str:
-    """Build market admin header row."""
-    from quart import url_for
+def _market_admin_header_html(ctx: dict, *, oob: bool = False, selected: str = "") -> str:
+    """Build market admin header row — delegates to shared helper."""
+    slug = (ctx.get("post") or {}).get("slug", "")
+    return post_admin_header_html(ctx, slug, oob=oob, selected=selected)
 
-    link_href = url_for("market.admin.admin")
-    return render(
-        "menu-row",
-        id="market-admin-row", level=3,
-        link_href=link_href, link_label="admin", icon="fa fa-cog",
-        child_id="market-admin-header-child", oob=oob,
-    )
+
+# ---------------------------------------------------------------------------
+# Page admin (/<slug>/admin/) — post-level admin for markets
+# ---------------------------------------------------------------------------
+
+async def render_page_admin_page(ctx: dict) -> str:
+    """Full page: page-level market admin."""
+    slug = (ctx.get("post") or {}).get("slug", "")
+    admin_hdr = post_admin_header_html(ctx, slug, selected="markets")
+    hdr = root_header_html(ctx)
+    child = _post_header_html(ctx) + admin_hdr
+    hdr += render("header-child", inner_html=child)
+    content = '<div id="main-panel"><div class="p-4 text-stone-500">Market admin</div></div>'
+    return full_page(ctx, header_rows_html=hdr, content_html=content)
+
+
+async def render_page_admin_oob(ctx: dict) -> str:
+    """OOB response: page-level market admin."""
+    slug = (ctx.get("post") or {}).get("slug", "")
+    oobs = post_admin_header_html(ctx, slug, oob=True, selected="markets")
+    content = '<div id="main-panel"><div class="p-4 text-stone-500">Market admin</div></div>'
+    return oob_page(ctx, oobs_html=oobs, content_html=content)
 
 
 # ---------------------------------------------------------------------------