feat: let a mood exclude tags, and widen the eighties one to the canon

The eighties mood selected on synth-specific tags only, on the grounds that the
bare `80s` tag drags in Def Leppard and Bon Jovi. Checking the canon against
live Last.fm pages shows what that costs. Eurythmics is tagged 80s, new wave,
pop, female vocalists, synth pop -- four of those five are tags no mood may use.
Frankie Goes to Hollywood is tagged 80s, new wave, pop, british, dance, and
survives only on new wave. An act tagged purely 80s, pop and dance, which is a
great deal of eighties pop, was missed outright.

Two spellings also matter more than the census suggested. Of Depeche Mode, Duran
Duran, Eurythmics and Frankie Goes to Hollywood, three carry "synth pop" with a
space and only one carries "synthpop" without. The census could not show this
because it only sees artists already in the library; the spelling that was kept
was the rarer one.

Add an `exclude` list to a mood. An excluded tag drops the artist outright
rather than docking their score, which is the only construction that expresses
"the eighties, but not the stadium rock" -- weighting cannot do it, because the
tag it would weight is the one both share. The synth acts do not carry hard rock
or hair metal, and that is the whole of the difference.

A mood may not both select on and exclude the same tag; that is rejected when
the definitions are read rather than silently producing nothing.

music_curator.py

@@ -1320,12 +1320,23 @@ DEFAULT_VIBES = (
     },
     {
         "name": "80s-synths",
-        # Without the bare `80s` tag, which in this library sits on Def Leppard
-        # and Bon Jovi rather than on anything with a synthesiser in it. The
-        # year window is kept as a second filter, not as the only one.
+        # `80s` is included, which on its own would drag in Def Leppard and Bon
+        # Jovi -- they carry it as heavily as Eurythmics does. The exclusion is
+        # what separates them: the stadium rock is also tagged hard rock and
+        # hair metal, and the synth acts are not. Weighting cannot do this,
+        # because the tag it would weight is the one they share.
+        #
+        # Both spellings of synth pop are listed. Of Depeche Mode, Duran Duran,
+        # Eurythmics and Frankie Goes to Hollywood, three carry "synth pop" with
+        # a space and only one carries "synthpop" without.
         "tags": [
-            "synthpop", "electropop", "new wave", "post-punk",
-            "post-punk revival", "new romantic",
+            "80s", "new wave", "synth pop", "synthpop", "synth-pop", "synthwave",
+            "electropop", "new romantic", "post-punk", "post-punk revival",
+        ],
+        "exclude": [
+            "hard rock", "hair metal", "glam metal", "glam rock", "heavy metal",
+            "metal", "arena rock", "aor", "nwobhm", "thrash metal",
+            "classic rock", "southern rock", "blues rock",
         ],
         "years": [1975, 1992],
     },
@@ -1358,6 +1369,13 @@ def load_vibes(path):
             raise ValueError(f"{path}: {name!r} is not a usable vibe name (a-z, 0-9, -)")
         if not vibe.get("tags"):
             raise ValueError(f"{path}: vibe {name!r} lists no tags")
+        overlap = {str(tag).casefold() for tag in vibe["tags"]} & {
+            str(tag).casefold() for tag in vibe.get("exclude", [])
+        }
+        if overlap:
+            raise ValueError(
+                f"{path}: vibe {name!r} both selects on and excludes {sorted(overlap)}"
+            )
     return tuple(loaded)
 
 
@@ -1464,8 +1482,24 @@ def build_vibe_playlists(store, vibes, mirror_root, library_root, limit, now):
     for vibe in vibes:
         tags = [str(tag).strip().casefold() for tag in vibe["tags"]]
         placeholders = ",".join("?" * len(tags))
-        years = vibe.get("years")
         parameters = [*tags, vibe.get("min_score", VIBE_MIN_SCORE)]
+
+        # An exclusion drops the artist outright rather than docking their
+        # score. It is the only way to write "the eighties, but not the stadium
+        # rock": those artists carry `80s` as heavily as the synth acts do, so
+        # no amount of weighting separates them -- but they also carry `hard
+        # rock`, and the synth acts do not.
+        excluded = [str(tag).strip().casefold() for tag in vibe.get("exclude", [])]
+        exclude_clause = ""
+        if excluded:
+            exclude_clause = (
+                " AND NOT EXISTS (SELECT 1 FROM artist_tag x"
+                "                  WHERE x.norm_artist = a.norm_name"
+                f"                   AND x.tag IN ({','.join('?' * len(excluded))}))"
+            )
+            parameters += excluded
+
+        years = vibe.get("years")
         year_clause = ""
         if years:
             year_clause = (
@@ -1488,7 +1522,7 @@ def build_vibe_playlists(store, vibes, mirror_root, library_root, limit, now):
               JOIN lidarr_artist a ON a.id = t.artist_id
               JOIN vibe v ON v.norm_artist = a.norm_name
               LEFT JOIN lidarr_album al ON al.id = t.album_id
-             WHERE {PLAYABLE}{year_clause}
+             WHERE {PLAYABLE}{exclude_clause}{year_clause}
              ORDER BY ((t.id * {SHUFFLE_MULTIPLIER}) + ?) % {SHUFFLE_MODULUS}
              LIMIT ?
         """