[mod] client/simple: client plugins (#5406)

* [mod] client/simple: client plugins

Defines a new interface for client side *"plugins"* that coexist with server
side plugin system. Each plugin (e.g., `InfiniteScroll`) extends the base
`ts Plugin`. Client side plugins are independent and lazy‑loaded via `router.ts`
when their `load()` conditions are met. On each navigation request, all
applicable plugins are instanced.

Since these are client side plugins, we can only invoke them once DOM is fully
loaded. E.g. `Calculator` will not render a new `answer` block until fully
loaded and executed.

For some plugins, we might want to handle its availability in `settings.yml`
and toggle in UI, like we do for server side plugins. In that case, we extend
`py Plugin` instancing only the information and then checking client side if
[`settings.plugins`](https://github.com/inetol/searxng/blob/1ad832b1dc33f3f388da361ff2459b05dc86a164/client/simple/src/js/toolkit.ts#L134)
array has the plugin id.

* [mod] client/simple: rebuild static

2 files changed, 3 insertions, 99 deletions

diff --git a/tests/unit/settings/user_settings.yml b/tests/unit/settings/user_settings.yml
index 39c4d9c07..32affc33f 100644
--- a/tests/unit/settings/user_settings.yml
+++ b/tests/unit/settings/user_settings.yml
@@ -37,6 +37,9 @@ plugins:
   searx.plugins.calculator.SXNGPlugin:
     active: true
 
+  searx.plugins.infinite_scroll.SXNGPlugin:
+    active: false
+
   searx.plugins.hash_plugin.SXNGPlugin:
     active: true
 
diff --git a/tests/unit/test_plugin_calculator.py b/tests/unit/test_plugin_calculator.py
deleted file mode 100644
index ca5c5d6c8..000000000
--- a/tests/unit/test_plugin_calculator.py
+++ /dev/null
@@ -1,99 +0,0 @@
-# SPDX-License-Identifier: AGPL-3.0-or-later
-# pylint: disable=missing-module-docstring,disable=missing-class-docstring,invalid-name
-
-import warnings
-
-from parameterized.parameterized import parameterized
-
-import searx.plugins
-import searx.preferences
-
-from searx.extended_types import sxng_request
-from searx.result_types import Answer
-
-from tests import SearxTestCase
-from .test_utils import random_string
-from .test_plugins import do_post_search
-
-
-# Reporting the DeprecationWarning once should be sufficient when running tests
-warnings.filterwarnings("once", category=DeprecationWarning)
-
-
-class PluginCalculator(SearxTestCase):
-
-    def setUp(self):
-        super().setUp()
-        engines = {}
-
-        self.storage = searx.plugins.PluginStorage()
-        self.storage.load_settings({"searx.plugins.calculator.SXNGPlugin": {"active": True}})
-        self.storage.init(self.app)
-        self.pref = searx.preferences.Preferences(["simple"], ["general"], engines, self.storage)
-        self.pref.parse_dict({"locale": "en"})
-
-    def test_plugin_store_init(self):
-        self.assertEqual(1, len(self.storage))
-
-    def test_pageno_1_2(self):
-        with self.app.test_request_context():
-            sxng_request.preferences = self.pref
-            query = "1+1"
-            answer = Answer(answer=f"{query} = {eval(query)}")  # pylint: disable=eval-used
-
-            search = do_post_search(query, self.storage, pageno=1)
-            self.assertIn(answer, search.result_container.answers)
-
-            search = do_post_search(query, self.storage, pageno=2)
-            self.assertEqual(list(search.result_container.answers), [])
-
-    def test_long_query_ignored(self):
-        with self.app.test_request_context():
-            sxng_request.preferences = self.pref
-            query = f"1+1 {random_string(101)}"
-            search = do_post_search(query, self.storage)
-            self.assertEqual(list(search.result_container.answers), [])
-
-    @parameterized.expand(
-        [
-            ("1+1", "2", "en"),
-            ("1-1", "0", "en"),
-            ("1*1", "1", "en"),
-            ("1/1", "1", "en"),
-            ("1**1", "1", "en"),
-            ("1^1", "1", "en"),
-            ("1,000.0+1,000.0", "2,000", "en"),
-            ("1.0+1.0", "2", "en"),
-            ("1.0-1.0", "0", "en"),
-            ("1.0*1.0", "1", "en"),
-            ("1.0/1.0", "1", "en"),
-            ("1.0**1.0", "1", "en"),
-            ("1.0^1.0", "1", "en"),
-            ("1.000,0+1.000,0", "2.000", "de"),
-            ("1,0+1,0", "2", "de"),
-            ("1,0-1,0", "0", "de"),
-            ("1,0*1,0", "1", "de"),
-            ("1,0/1,0", "1", "de"),
-            ("1,0**1,0", "1", "de"),
-            ("1,0^1,0", "1", "de"),
-        ]
-    )
-    def test_localized_query(self, query: str, res: str, lang: str):
-        with self.app.test_request_context():
-            self.pref.parse_dict({"locale": lang})
-            sxng_request.preferences = self.pref
-            answer = Answer(answer=f"{query} = {res}")
-
-            search = do_post_search(query, self.storage)
-            self.assertIn(answer, search.result_container.answers)
-
-    @parameterized.expand(
-        [
-            "1/0",
-        ]
-    )
-    def test_invalid_operations(self, query):
-        with self.app.test_request_context():
-            sxng_request.preferences = self.pref
-            search = do_post_search(query, self.storage)
-            self.assertEqual(list(search.result_container.answers), [])