feat(cloudflare): add linearvoid-media edge worker for R2 HLS delivery

Replace the ad-hoc `worker.js` with a self-contained `linearvoid-media`
worker under `infrastructure/cloudflare/` that owns `media.linearvoid.tv`.
It serves HLS objects from the R2 bucket, enforcing immutable Cache-Control
on segments, a short TTL on live manifests, plus HLS CORS, OPTIONS
preflight, Range support, and a `/health` probe. Includes wrapper config
with production domain, Vitest unit tests, Miniflare R2 integration tests,
automated deploy workflow, and docs updates.

infrastructure/cloudflare/package.json

@@ -0,0 +1,20 @@
+{
+  "name": "linearvoid-media-worker",
+  "version": "1.0.0",
+  "private": true,
+  "description": "Linear Void media edge worker: serves HLS from R2 on media.linearvoid.tv with immutable segment caching.",
+  "type": "module",
+  "scripts": {
+    "dev": "wrangler dev",
+    "start": "wrangler dev",
+    "deploy": "wrangler deploy",
+    "deploy:production": "wrangler deploy --env production",
+    "test": "vitest run",
+    "test:watch": "vitest"
+  },
+  "devDependencies": {
+    "miniflare": "^4.0.0",
+    "vitest": "^4.1.10",
+    "wrangler": "^4.0.0"
+  }
+}