feat(tenancy): add team invitation acceptance page

New standalone page at /store/{store_code}/invitation/accept?token=xxx
where invited team members can:
- Review their name and email (pre-filled from invitation)
- Set their password
- Accept the invitation

Page handles all routing modes (dev path, platform path, prod subdomain,
custom domain) via store context middleware. After acceptance, redirects
to the platform-aware store login page.

New service method get_invitation_info() validates the token and returns
invitation details without modifying anything.

Error states: expired token, already accepted, invalid token.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/modules/tenancy/routes/pages/store.py

@@ -10,7 +10,7 @@ Store pages for authentication and account management:
 - Settings
 """
 
-from fastapi import APIRouter, Depends, Request
+from fastapi import APIRouter, Depends, Query, Request
 from fastapi.responses import HTMLResponse, RedirectResponse
 from sqlalchemy.orm import Session
 
@@ -100,6 +100,43 @@ async def store_login_page(
     )
 
 
+@router.get(
+    "/invitation/accept", response_class=HTMLResponse, include_in_schema=False
+)
+async def store_invitation_accept_page(
+    request: Request,
+    token: str = Query(..., description="Invitation token from email"),
+    store_code: str = Depends(get_resolved_store_code),
+    db: Session = Depends(get_db),
+):
+    """
+    Render invitation acceptance page.
+
+    Public route — no auth required. Validates the token and shows a form
+    to review name and set password.
+    """
+    from app.modules.tenancy.services.store_team_service import store_team_service
+
+    language = getattr(request.state, "language", "en")
+    platform_code = getattr(request.state, "platform_code", None)
+
+    # Get invitation info (without accepting it)
+    info = store_team_service.get_invitation_info(db, token)
+
+    return templates.TemplateResponse(
+        "tenancy/store/invitation-accept.html",
+        {
+            "request": request,
+            "store_code": store_code,
+            "platform_code": platform_code,
+            "frontend_type": "store",
+            "token": token,
+            "invitation": info,
+            **get_jinja2_globals(language),
+        },
+    )
+
+
 # ============================================================================
 # AUTHENTICATED ROUTES (Store Users Only)
 # ============================================================================