feat: detect & link album mentions, not just artists (closes task/album-detection)

Source: task/album-detection (objective/linker-improvements) — project brief asks for artist OR album linking; MVP linked artists only.

- service/lib.js: pickAlbum (the exact-name gate, named for the album path) + linkResult now carries kind:"artist"|"album" (additive; defaults to artist so older clients keep working).
- service/resolver.js: one Spotify type=artist,album search per candidate, exact-match against either; returns {url,kind}; cache key includes the kind hint. resolveOne/resolveAll thread the LLM kind hint through.
- service/llm.js: parseClassification now returns Map(name -> "artist"|"album") so album-kind candidates route to the album path (.has() still works like the old Set).
- extension/extract.js: albumMatchesIn over two precise signals (quoted strings + album cue phrases "the album X", "X LP/EP"), folded into allMatchesIn.
- extension/content.js + styles.css: album links render italicised (.rsl-album) with an album tooltip; artist behavior unchanged.
- Tests: new pure-logic coverage in lib.test.js / llm.test.js / extract.test.cjs (album shaping, Map-kind routing, album candidate extraction). scripts/check.sh green.
- README.md + AGENTS.md: document album linking.

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

README.md

@@ -1,19 +1,22 @@
 # Reddit → Spotify / Bandcamp linker
 
 A Firefox extension that, while you browse a Reddit thread, finds **artist / band
-names** in the comments (and the post body) and turns them into inline links to
-**Spotify** and **Bandcamp** — so a recommendation thread like
+names and album titles** in the comments (and the post body) and turns them into
+inline links to **Spotify** and **Bandcamp** — so a recommendation thread like
 [this one](https://www.reddit.com/r/SlamDeathMetal/comments/1txh2r1/) becomes a
-list of clickable artists instead of names you have to copy-paste into search.
+list of clickable artists and albums instead of names you have to copy-paste into
+search.
 
-The hard part is *"which words are artists and which aren't?"*. Rather than guess
-with client-side rules, the extension hands candidate names to a tiny local
+The hard part is *"which words are artists/albums and which aren't?"*. Rather than
+guess with client-side rules, the extension hands candidate names to a tiny local
 **resolver service** that confirms each one and only links the names that are
-really artists. The resolver confirms names two ways (you enable either or both):
-**Spotify** (exact-name match → direct artist pages) and an optional **local LLM**
-via ollama (classifies which candidates are artists/albums). A confirmed name
-links to its Spotify artist page when available, otherwise to a Google search for
-"<name> bandcamp".
+really artists or albums. The resolver confirms names two ways (you enable either
+or both): **Spotify** (exact-name match across artists **and** albums → direct
+Spotify pages) and an optional **local LLM** via ollama (classifies which
+candidates are artists/albums). A confirmed name links to its Spotify
+artist/album page when available, otherwise to a Google search for
+"<name> bandcamp". Album links are italicised so you can tell an album from an
+artist at a glance.
 
 ```
  reddit page                 content script                 resolver service
@@ -56,8 +59,9 @@ warns at startup and nothing links.
 ### Spotify credentials (one of the two gates)
 
 Spotify does two jobs: it **gates** a name (a candidate links only when Spotify has
-that artist by exact name match) and supplies the **direct** artist-page link. To
-enable it:
+that **artist or album** by exact name match) and supplies the **direct** Spotify
+page link. A single search call covers both types, so albums confirm and link with
+no extra setup. To enable it:
 
 1. Create a free app at <https://developer.spotify.com/dashboard> and copy its
    **Client ID** and **Client Secret**.
@@ -129,8 +133,9 @@ with `xpinstall.signatures.required = false`.)
 
 1. Make sure the resolver service is running.
 2. Open any Reddit comments thread (a URL with `/comments/` in it).
-3. Artist names become a single link — to **Spotify** if the artist is on Spotify,
-   otherwise to **Bandcamp** — colour-coded (green = Spotify, teal = Bandcamp). New
+3. Artist names and album titles become a single link — to **Spotify** if it's on
+   Spotify, otherwise to **Bandcamp** — colour-coded (green = Spotify, blue =
+   Google/Bandcamp); album links are italicised so they read as albums. New
    comments loaded as you scroll are linked automatically.
 4. The toolbar icon shows the extension is active; its badge shows how many links were
    added on the current page.
@@ -162,13 +167,17 @@ let the content script reach it).
 
 ## Limitations (MVP)
 
-- **Detection is mostly capitalization-based**, with a cue-phrase pass that also catches
-  lowercase names right after "check out / by / fan of / recommend …". Names split across
-  inline formatting (e.g. **bold** mid-name) can still be missed. The resolver's
+- **Artist detection is mostly capitalization-based**, with a cue-phrase pass that also
+  catches lowercase names right after "check out / by / fan of / recommend …". Names split
+  across inline formatting (e.g. **bold** mid-name) can still be missed. The resolver's
   exact-name match keeps false *positives* low; the trade-off is some false *negatives*.
-- **Links are direct to Spotify when Spotify has the artist**; otherwise a confirmed
-  name links to a Google search for "<name> bandcamp" (which surfaces the artist's
-  Bandcamp page).
+- **Album detection leans on two precise signals** — quoted titles (`"Reek of Putrefaction"`)
+  and album cue phrases ("the album X", "X LP/EP"). Album free-text is noisier than artist
+  names, so it deliberately over-generates only from these cues and lets the Spotify
+  exact-album match (and/or the LLM) be the precision filter. A bare album title written with
+  no quotes or cue may be missed.
+- **Links are direct to Spotify when Spotify has the artist/album**; otherwise a confirmed
+  name links to a Google search for "<name> bandcamp" (which surfaces the Bandcamp page).
 - **Without Spotify creds or the LLM, nothing links** — at least one gate must be
   configured.
 - The optional LLM adds a little latency on the **first** call (ollama warms the