Bundle sdk for browser (no polyfills required!), and for Node.js (#3358)

### Summary

Introduces a Rollup-based bundling system for the SDK, enabling proper
platform-specific builds for both Node.js and browser environments with
architectural refactoring to support environment-specific code via the
`@/` path alias pattern.

### Key Changes

- **Rollup bundling pipeline** - Added `rollup.config.mts` producing
multiple output formats:
  - Node.js: ESM (`.js`) and CJS (`.cjs`)
  - Browser: ESM (`.js`) and CJS (`.cjs`)  
  - UMD: Regular and minified builds for `<script>` tag usage

- **Platform-specific code organization** - Introduced `_browser/` and
`_nodejs/` directories with `@/` path alias that resolves to the correct
platform at build time:
  - `Persistence`: Browser uses IndexedDB, Node.js uses SQLite
- `createRSAKeyPair`: Browser uses WebCrypto, Node.js uses native crypto

- **TypeScript configuration refactor** - Split into
`tsconfig.node.json` and `tsconfig.browser.json` for separate
compilation targets

- **Browser compatibility improvements**:
  - Replaced `crypto.randomBytes` with `@noble/post-quantum/utils`
  - Added `publicEncrypt` and `privateDecrypt` to `@streamr/utils`
- Aliased `stream` → `readable-stream` and `timers` →
`timers-browserify`

### Known Limitations

- `Persistence.exists()` is not implemented for browser (throws error) -
this functionality is Node.js only

### Future Considerations

- In the SDK, browser-specific code lives in `src/_browser/` and
Node.js-specific code in `src/_nodejs/`. This underscore-prefixed
directory pattern could be applied to other packages in the monorepo
that need platform-specific implementations.

Author: mondoreale

docs/docs/usage/sdk/how-to-use.md

@@ -38,7 +38,7 @@ Node.js `20` is the minimum required version, ideally version 22 and later. Node
 For usage in the browser include the latest build, e.g. by including a `<script>` tag pointing at a CDN:
 
 ```html
-<script src="https://unpkg.com/@streamr/sdk/streamr-sdk.web.js"></script>
+<script src="https://unpkg.com/@streamr/sdk/exports-umd.js"></script>
 ```
 
 #### Browser extension

package-lock.json

@@ -50,6 +50,7 @@
     "rimraf": "^6.1.2",
     "rollup": "^4.55.1",
     "rollup-plugin-dts": "^6.3.0",
+    "ts-loader": "^9.5.4",
     "tsx": "^4.21.0",
     "webpack": "^5.103.0",
     "webpack-cli": "^6.0.1"

packages/browser-test-runner/package.json

@@ -41,7 +41,7 @@ The Streamr SDK is built for the browser and Node.js environments.
 
 **Browser (Website/WebApps)**
 - For usage in the browser include the latest build, e.g. by including a `<script>` tag pointing at a CDN:
-- `<script src="https://unpkg.com/@streamr/sdk@latest/streamr-sdk.web.min.js"></script>`
+- `<script src="https://unpkg.com/@streamr/sdk@latest/exports-umd.min.js"></script>`
 - To use within React, please see [streamr-client-react](https://github.com/streamr-dev/streamr-client-react)
 
 **Browser extension**

packages/sdk/README.md

@@ -1,5 +1,5 @@
 {
-  "extends": "..",
+  "extends": "../tsconfig.node.json",
   "include": [
     "**/*"
   ]

packages/sdk/bin/tsconfig.json

@@ -0,0 +1,35 @@
+import {
+    createKarmaConfig as createKarmaConfigUtil,
+    createWebpackConfig,
+} from '@streamr/browser-test-runner'
+import { resolve } from 'node:path'
+
+export function createKarmaConfig(testPaths: string[]): ReturnType<typeof createKarmaConfigUtil> {
+    return createKarmaConfigUtil(
+        testPaths,
+        createWebpackConfig({
+            libraryName: 'sdk',
+            alias: {
+                '@jest/globals': resolve(
+                    __dirname,
+                    'test/test-utils/jestGlobalsMock.ts'
+                ),
+                '@streamr/dht': resolve(__dirname, '../dht/dist/exports-browser.cjs'),
+                '@': resolve(__dirname, 'src/_browser'),
+            },
+            fallback: {
+                v8: false,
+                module: false,
+            },
+            externals: {
+                http: 'HTTP',
+                ws: 'WebSocket',
+                'node-datachannel': 'commonjs node-datachannel',
+                express: 'Express',
+                'node:stream/web': 'stream/web',
+                'node:timers/promises': 'timers/promises',
+            },
+        }),
+        __dirname
+    )
+}

packages/sdk/createKarmaConfig.ts

@@ -7,9 +7,12 @@ const config: Config.InitialOptions = {
     setupFilesAfterEnv: [
         ...defaultConfig.setupFilesAfterEnv,
         './src/setupTsyringe.ts',
-        './test/test-utils/customMatchers.ts',
+        './test/test-utils/setupCustomMatchers.ts',
         '@streamr/test-utils/setupCustomMatchers',
     ],
+    moduleNameMapper: {
+        "^@/(.*)$": "<rootDir>/src/_nodejs/$1",
+    },
 }
 
 export default config

packages/sdk/fix-esm.sh

@@ -1,19 +1,22 @@
-// eslint-disable-next-line import/no-extraneous-dependencies
-import { GitRevisionPlugin } from 'git-revision-webpack-plugin'
+import { execSync } from 'child_process'
 import pkg from './package.json'
 
+const execGitCommand = (command: string): string => {
+    try {
+        return execSync(command, { encoding: 'utf8' }).trim()
+    } catch {
+        return ''
+    }
+}
+
 export default async function setup(): Promise<void> {
     if (process.env.GIT_VERSION) {
         return
     }
 
-    const gitRevisionPlugin = new GitRevisionPlugin()
-
-    const [GIT_VERSION, GIT_COMMITHASH, GIT_BRANCH] = await Promise.all([
-        gitRevisionPlugin.version(),
-        gitRevisionPlugin.commithash(),
-        gitRevisionPlugin.branch(),
-    ])
+    const GIT_VERSION = execGitCommand('git describe --always --tags')
+    const GIT_COMMITHASH = execGitCommand('git rev-parse HEAD')
+    const GIT_BRANCH = execGitCommand('git rev-parse --abbrev-ref HEAD')
 
     Object.assign(process.env, {
         version: pkg.version,

packages/sdk/jest.config.ts

@@ -1,4 +1,2 @@
-import webpackConfig from './webpack-karma.config'
-import { createKarmaConfig } from '@streamr/browser-test-runner'
-
-export default createKarmaConfig(['test/end-to-end/**/*.ts'], webpackConfig, __dirname)
+import { createKarmaConfig } from './createKarmaConfig'
+export default createKarmaConfig(['test/end-to-end/**/*.ts'])