Use typescript for webpack config (#32507)

* Move declaration.d.ts to @types

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Load customisations.json without `require`

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Remove webpack rule from when we were consuming shared-components ts vs js

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Avoid hardcoding paths to modules in webpack config

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Convert webpack config to typescript

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Stub js webpack/postcss plugins

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Patch broken rollup types until https://github.com/getsentry/sentry-javascript-bundler-plugins/pull/870 is released

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Install @types/postcss-import

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Fix fdir relying on @types/picomatch

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Update pnpm-lock.yaml

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

---------

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

@types/declaration.d.ts

@@ -0,0 +1,8 @@
+/*
+ * Copyright 2025 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+declare module "*.module.css";

@types/postcss-easings.d.ts

@@ -0,0 +1,10 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+declare module "postcss-easings" {
+    export default function (): void;
+}

@types/postcss-hexrgba.d.ts

@@ -0,0 +1,10 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+declare module "postcss-hexrgba" {
+    export default function (): void;
+}

@types/postcss-mixins.d.ts

@@ -0,0 +1,10 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+declare module "postcss-mixins" {
+    export default function (): void;
+}

@types/webpack-version-file-plugin.d.ts

@@ -0,0 +1,19 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+declare module "webpack-version-file-plugin" {
+    interface Opts {
+        outputFile: string;
+        template?: string;
+        templateString?: string;
+        extras?: Record<string, string>;
+    }
+
+    export default class VersionFilePlugin {
+        public constructor(opts: Opts);
+    }
+}