Rename the Fixer to Tune-up

Tab, URL (#/pair/<id>/tune-up; old fixer links still work), job names,
History trigger and docs now say Tune-up.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -7,12 +7,12 @@ up disk space only once, while both libraries keep looking exactly the same to P
 It ships as a single Go binary with an embedded React web UI and SQLite state, packaged as a small Docker image, in the style of
 [qui](https://github.com/autobrr/qui).
 
-## Workflow: fix, organize, then link
+## Workflow: tune up, then link
 
 Each library pair has a **type**: **Music** (recommended layout `Artist/Album/01 Title.flac`) or **Soundtracks** for video game and film
 soundtracks (`Album/01 Title.flac`, named by game or film). The type sets the default naming; the *Organize* tab can change it.
 
-The **Fixer** tab takes each library through the same steps, the **master first, then the slave**, and then links the two:
+The **Tune-up** tab takes each library through the same steps, the **master first, then the slave**, and then links the two:
 
 1. **Folder structure.** Every album in its own folder at the right depth. Songs outside an album folder move into one named from their
    tags; extra folders around an album (a composer folder around a soundtrack, `Metal/Artist/Album`, a `FLAC` folder inside an album) are