Remove randomness from flaky twenty-front Storybook stories (#21594)

Several twenty-front Storybook stories were flagged flaky by Argos
because they render different pixels across runs. This removes the
non-determinism behind them.

**What changed**
- **Images** — replaced random `picsum.photos` URLs in the Logo and
TabList stories with the existing `AVATAR_URL_MOCK`, and added global
MSW handlers in `.storybook/preview.tsx` that serve a deterministic
image for every remote host (picsum, twenty-icons.com,
twentyhq.github.io, etc.) so no story depends on a network image load.
- **Numbers** — the line-chart story built its data with
`Math.random()`; now uses a deterministic formula.
- **Dates** — the terminal "long output" story stamped its lines with
`new Date()`; now uses a fixed base timestamp. The calendar-channel
date/time format previews and example event used render-time
`Date.now()`/`new Date()` in shared components; they now use a fixed
reference date (`DateTimeSettingsPreviewDate`).
- **Lazy-load timing** — the date-picker story now waits for the
lazily-loaded calendar before the snapshot.

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packages/twenty-front/src/modules/ui/input/components/internal/date/components/__stories__/InternalDatePicker.stories.tsx

@@ -31,7 +31,16 @@ const meta: Meta<typeof DateTimePicker> = {
 export default meta;
 type Story = StoryObj<typeof DateTimePicker>;
 
-export const Default: Story = {};
+export const Default: Story = {
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    await canvas.findByRole(
+      'button',
+      { name: 'Select month and year' },
+      { timeout: 10000 },
+    );
+  },
+};
 
 export const WithOpenMonthSelect: Story = {
   play: async ({ canvasElement }) => {

packages/twenty-front/src/modules/ui/layout/tab-list/components/__stories__/Tablist.stories.tsx

@@ -10,10 +10,13 @@ import {
   IconPhone,
   IconUser,
 } from 'twenty-ui-deprecated/display';
-import { ComponentWithRouterDecorator } from 'twenty-ui-deprecated/testing';
+import {
+  AVATAR_URL_MOCK,
+  ComponentWithRouterDecorator,
+} from 'twenty-ui-deprecated/testing';
 
 const tabs = [
-  { id: 'general', title: 'General', logo: 'https://picsum.photos/200' },
+  { id: 'general', title: 'General', logo: AVATAR_URL_MOCK },
   { id: 'contacts', title: 'Contacts', Icon: IconUser },
   { id: 'messages', title: 'Messages', Icon: IconMail },
   { id: 'calls', title: 'Calls', Icon: IconPhone },
@@ -23,7 +26,7 @@ const tabs = [
   {
     id: 'time',
     title: 'Time Tracking',
-    logo: 'https://picsum.photos/192/192',
+    logo: AVATAR_URL_MOCK,
   },
   {
     id: 'activity',