feat: reddit -> spotify/bandcamp artist linker MVP (extension + resolver service)

Firefox MV2 content script that detects artist/band names in reddit comment
threads and rewrites them inline into Spotify + Bandcamp links, backed by a tiny
zero-dependency Node resolver that confirms each candidate against the Spotify Web
API (direct links) or MusicBrainz (zero-setup, search links). Includes build +
install instructions in the README.

Source: project/reddit-spotify-linker (user 2026-06-12) + user message 2026-06-14
"Full vibe code, small service, minimal code."

Closes task/resolver-service, closes task/firefox-extension, closes task/docs-and-publish
(plan/mvp-build, objective/ship-mvp-linker).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

extension/manifest.json

@@ -0,0 +1,24 @@
+{
+  "manifest_version": 2,
+  "name": "Reddit → Spotify/Bandcamp linker",
+  "version": "0.1.0",
+  "description": "Turns artist/album names in reddit comments into Spotify and Bandcamp links.",
+  "browser_specific_settings": {
+    "gecko": {
+      "id": "reddit-spotify-linker@paul.yapplesauce.com",
+      "strict_min_version": "109.0"
+    }
+  },
+  "permissions": [
+    "http://localhost:8787/*",
+    "http://127.0.0.1:8787/*"
+  ],
+  "content_scripts": [
+    {
+      "matches": ["*://*.reddit.com/*"],
+      "js": ["content.js"],
+      "css": ["styles.css"],
+      "run_at": "document_idle"
+    }
+  ]
+}