[ADD] membership_status_in_portal: portal membership status badge

Add a generic module displaying the connected portal user's membership
status in the account sidebar, below the "Edit information" link.

The native Odoo membership label (``res.partner.membership_state`` from
the ``membership`` module) is shown as a colored badge:
- green (``text-bg-success``) for free / paid members;
- yellow (``text-bg-warning``) for waiting / invoiced members;
- red (``text-bg-danger``) otherwise.

Color, icon and label are computed in the QWeb template; no model or
field is added. Includes HttpCase tests covering member and non-member
rendering and asserting no action button is rendered.

membership_status_in_portal/tests/__init__.py

@@ -0,0 +1 @@
+from . import test_portal_sidebar

membership_status_in_portal/tests/test_portal_sidebar.py

@@ -0,0 +1,66 @@
+import re
+
+from odoo.tests import HttpCase, tagged
+
+
+@tagged("post_install", "-at_install")
+class MembershipStatusPortalCase(HttpCase):
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        cls.portal_group = cls.env.ref("base.group_portal")
+
+    def _create_portal_user(self, login, **partner_vals):
+        partner = self.env["res.partner"].create(
+            {
+                "name": login,
+                "lang": self.env.lang or "en_US",
+                **partner_vals,
+            }
+        )
+        return self.env["res.users"].create(
+            {
+                "name": login,
+                "login": login,
+                "password": login,
+                "partner_id": partner.id,
+                "groups_id": [(6, 0, [self.portal_group.id])],
+            }
+        )
+
+    def _membership_label(self, partner):
+        selection = self.env["res.partner"].fields_get(["membership_state"])[
+            "membership_state"
+        ]["selection"]
+        return dict(selection)[partner.membership_state]
+
+    def _open_my_home(self, user):
+        self.authenticate(user.login, user.password)
+        response = self.url_open("/my/home")
+        self.assertEqual(response.status_code, 200)
+        return response.text
+
+    def _extract_membership_block(self, html):
+        match = re.search(r'<div class="o_membership_state.*?</div>', html, re.DOTALL)
+        self.assertIsNotNone(match, "membership status block not found on /my/home")
+        return match.group(0)
+
+    def test_non_member_sees_status_without_button(self):
+        user = self._create_portal_user("nonmember")
+        self.assertEqual(user.partner_id.membership_state, "none")
+
+        block = self._extract_membership_block(self._open_my_home(user))
+
+        self.assertIn(self._membership_label(user.partner_id), block)
+        self.assertNotIn("<button", block)
+        self.assertNotIn("<a ", block)
+
+    def test_member_sees_status_without_button(self):
+        user = self._create_portal_user("member", free_member=True)
+        self.assertEqual(user.partner_id.membership_state, "free")
+
+        block = self._extract_membership_block(self._open_my_home(user))
+
+        self.assertIn(self._membership_label(user.partner_id), block)
+        self.assertNotIn("<button", block)
+        self.assertNotIn("<a ", block)