feat(analytics): connect Umami analytics across www, docs, and static services (#49)

## Summary of Changes

- **`@ermnvldmr/ssg`**: Added extensible `AnalyticsProvider` interface,
`umamiAnalytics` integration in `@ermnvldmr/ssg/dev`, and runtime client
analytics dispatchers (`trackEvent`, `identifySession`).
- **`services/docs`**: Configured native Hextra Umami parameters in
`hugo.yaml` (`docs.ermnvldmr.com` with UUID
`fbdadf3f-3484-4186-a2c2-cedcf76cf44f`).
- **`services/www`**: Injected Umami tracking provider into
`rsbuild.config.ts` (`ermnvldmr.com`, `www.ermnvldmr.com` with UUID
`4fca5ac2-4fe4-4626-b708-933c37bfe918`).
- **`services/static`**: Injected Umami tracking provider into
`rsbuild.config.ts` (`static.ermnvldmr.com` with UUID
`0831532a-2cec-4955-8f5b-452d8bba96d8`).
- **Environment & Privacy**: Injections are automatically disabled in
development builds. Configured `data-domains` filtering and
`data-do-not-track="true"`.

## Verification
- `pnpm typecheck`: Passed (0 errors)
- `pnpm lint`: Passed (0 warnings)
- `pnpm test`: Passed (all unit test suites)
- `pnpm build`: Passed clean workspace build and pre-rendered SSG
injection

---
Disclosure: I'm an AI assistant helping Vladimir Eremin; I'm not
Vladimir Eremin.

services/www/rsbuild.config.ts

@@ -1,6 +1,11 @@
 import { createReadStream, existsSync } from 'node:fs';
 import { extname, join, sep } from 'node:path';
-import { defineSSGServiceConfig, discoverEntries, mergeConfig } from '@ermnvldmr/ssg/dev';
+import {
+  defineSSGServiceConfig,
+  discoverEntries,
+  mergeConfig,
+  umamiAnalytics,
+} from '@ermnvldmr/ssg/dev';
 import { THEME_INIT_SCRIPT, THEME_INIT_STYLES } from '@ermnvldmr/ui/dev';
 import { localeRsbuildConfig } from '@ermnvldmr/i18n/dev';
 import { RsdoctorRspackPlugin } from '@rsdoctor/rspack-plugin';
@@ -26,11 +31,20 @@ const MIME: Record<string, string> = {
   '.txt': 'text/plain',
 };
 
+const UMAMI_WWW_WEBSITE_ID = '4fca5ac2-4fe4-4626-b708-933c37bfe918';
 const locale = process.env.LOCALE ?? 'en';
 const fontBase = `/${locale}/static/font`;
 
 export default defineSSGServiceConfig(
   mergeConfig(localeRsbuildConfig(), {
+    analytics: [
+      umamiAnalytics({
+        serverUrl: 'https://umami.ermnvldmr.com',
+        websiteId: UMAMI_WWW_WEBSITE_ID,
+        domains: 'ermnvldmr.com,www.ermnvldmr.com',
+        doNotTrack: true,
+      }),
+    ],
     dev: {
       // Serve public/static/* at /static/* directly, bypassing server.base.
       // Without this, server.base (e.g. /en) would push the public dir to