feat(server): Compression Plugin (#869)

```ts
const handler = new RPCHandler(router, {
  plugins: [
    new CompressionPlugin(),
  ],
})
```

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- New Features
- Added a Compression Plugin for Fetch and Node adapters: configurable
encodings, threshold, and filter; automatically compresses compatible
responses and respects cache-control no-transform.

- Documentation
  - Added Compression Plugin docs and sidebar entry.
  - Clarified Body Limit example supports any compatible handler.

- Tests
- Added comprehensive Fetch and Node tests covering encodings,
thresholds, filters, headers, and error scenarios.

- Chores
  - Updated Dependabot to exclude the compression package.
- Added compression dev-dependencies and relaxed server build warnings.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: unnoq

.github/dependabot.yml

@@ -22,6 +22,7 @@ updates:
           - '@antfu/eslint-config'
           - 'eslint-plugin-*'
           - '@hey-api/*'
+          - compression # inline dependency
         update-types:
           - minor
           - patch

apps/content/.vitepress/config.ts

@@ -141,6 +141,7 @@ export default withMermaid(defineConfig({
             { text: 'Dedupe Requests', link: '/docs/plugins/dedupe-requests' },
             { text: 'Batch Requests', link: '/docs/plugins/batch-requests' },
             { text: 'Client Retry', link: '/docs/plugins/client-retry' },
+            { text: 'Compression', link: '/docs/plugins/compression' },
             { text: 'Body Limit', link: '/docs/plugins/body-limit' },
             { text: 'Simple CSRF Protection', link: '/docs/plugins/simple-csrf-protection' },
             { text: 'Strict GET method', link: '/docs/plugins/strict-get-method' },

apps/content/docs/plugins/body-limit.md

@@ -29,3 +29,7 @@ const handler = new RPCHandler(router, {
   ],
 })
 ```
+
+::: info
+The `handler` can be any supported oRPC handler, such as [RPCHandler](/docs/rpc-handler), [OpenAPIHandler](/docs/openapi/openapi-handler), or another custom handler.
+:::

apps/content/docs/plugins/compression.md

@@ -0,0 +1,33 @@
+---
+title: Compression Plugin
+description: A plugin for oRPC that compresses response bodies.
+---
+
+# Compression Plugin
+
+The **Compression Plugin** compresses response bodies to reduce bandwidth usage and improve performance.
+
+## Import
+
+Depending on your adapter, import the corresponding plugin:
+
+```ts
+import { CompressionPlugin } from '@orpc/server/node'
+import { CompressionPlugin } from '@orpc/server/fetch'
+```
+
+## Setup
+
+Add the plugin to your handler configuration:
+
+```ts
+const handler = new RPCHandler(router, {
+  plugins: [
+    new CompressionPlugin(),
+  ],
+})
+```
+
+::: info
+The `handler` can be any supported oRPC handler, such as [RPCHandler](/docs/rpc-handler), [OpenAPIHandler](/docs/openapi/openapi-handler), or another custom handler.
+:::

packages/server/build.config.ts

@@ -0,0 +1,9 @@
+import { defineBuildConfig } from 'unbuild'
+
+export default defineBuildConfig({
+  /**
+   * Disable warnings as errors because we need to inline the `compression` package,
+   * which is not ESModule-friendly.
+   */
+  failOnWarn: false,
+})

packages/server/package.json

@@ -135,7 +135,9 @@
     "cookie": "^1.0.2"
   },
   "devDependencies": {
+    "@types/compression": "^1.8.1",
     "@types/ws": "^8.18.1",
+    "compression": "^1.8.1",
     "crossws": "^0.4.1",
     "next": "^15.4.5",
     "supertest": "^7.1.4",