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.

README.md

@@ -0,0 +1,43 @@
+# RangerHQ Tuner
+
+Lightweight indie internet radio player for Chrome. Plays SomaFM in any browser tab. Manifest V3, vanilla JS, no telemetry.
+
+Sibling to [rangerhq-radio](https://git.davidtkeane.com/ranger/rangerhq-radio) (the WordPress version).
+
+## Tier 1 — MVP (current)
+
+- ✅ Manifest V3 + Offscreen API audio
+- ✅ Loads all SomaFM channels from `channels.json`
+- ✅ Pick a station, click Play, audio runs in background
+- ✅ Volume + state persisted across popup open/close
+- ✅ Catalogue cached 6h in `chrome.storage.local`
+- ✅ Source-adapter pattern in place for future networks
+
+## Install (developer mode)
+
+1. Open `chrome://extensions`
+2. Toggle **Developer mode** on (top right)
+3. Click **Load unpacked** → pick this folder (`rangerhq-tuner/`)
+4. Pin the extension to your toolbar (puzzle icon → pin)
+5. Click the toolbar icon → pick a SomaFM station → ▶ Play
+
+## Project layout
+
+```
+rangerhq-tuner/
+├── manifest.json
+└── src/
+    ├── background/service-worker.js   # message router, no audio here
+    ├── offscreen/offscreen.{html,js}  # the <audio> element host (MV3 needs this)
+    ├── popup/popup.{html,css,js}      # the toolbar UI
+    ├── sources/                       # extensibility seam
+    │   ├── base-source.js             # RadioSource interface (JSDoc)
+    │   ├── somafm.js                  # first concrete adapter
+    │   └── index.js                   # registry
+    ├── lib/                           # shared utilities
+    └── assets/icons/                  # 16/32/48/128 PNGs
+```
+
+## License
+
+GPL-2.0-or-later — matches the rest of the RangerHQ family.