feat: initial commit — RangerHQ Tuner v0.1.0 (Tier 1 MVP)

Chrome MV3 extension, browser-resident sibling to rangerhq-radio
(WP plugin). Plays SomaFM via the chrome.offscreen API + a source-
adapter pattern at src/sources/.

Architecture highlights:
- Audio runs in offscreen document — SW would get killed.
- Source-adapter pattern locks Tier 1 contract (RadioSource interface
  in src/sources/base-source.js). Adding a network = drop a file +
  register one line in src/sources/index.js.
- Vanilla JS, no build step. Pure ES modules.
- No telemetry, no third-party JS. Outbound only to somafm.com.
- Narrow permissions: offscreen + storage + somafm.com host_perms.
  No tabs, no <all_urls>, no webRequest.

22 files, ~30 min build following the saved plan at
~/.ranger-memory/projects/rangerhq-tuner-plan.md.

Tier 2 + Tier 3 (Web Store submission) not started.

manifest.json

@@ -0,0 +1,32 @@
+{
+  "manifest_version": 3,
+  "name": "RangerHQ Tuner",
+  "version": "0.1.0",
+  "description": "Lightweight indie internet radio player. Starts with SomaFM, extensible to more networks.",
+  "author": "David Keane",
+  "homepage_url": "https://davidtkeane.com/rangerhq-tuner",
+  "icons": {
+    "16":  "src/assets/icons/icon-16.png",
+    "32":  "src/assets/icons/icon-32.png",
+    "48":  "src/assets/icons/icon-48.png",
+    "128": "src/assets/icons/icon-128.png"
+  },
+  "action": {
+    "default_title": "RangerHQ Tuner",
+    "default_popup": "src/popup/popup.html",
+    "default_icon": {
+      "16": "src/assets/icons/icon-16.png",
+      "32": "src/assets/icons/icon-32.png"
+    }
+  },
+  "background": {
+    "service_worker": "src/background/service-worker.js",
+    "type": "module"
+  },
+  "permissions": ["offscreen", "storage"],
+  "host_permissions": [
+    "https://somafm.com/*",
+    "https://*.somafm.com/*"
+  ],
+  "minimum_chrome_version": "116"
+}