subwave: add 4 more 1996 shows, add artist-score floor to fix false match

Adds Tunecaster Rock Top 30 for 1996-01-13, 1996-04-13, 1996-07-13, and
1996-12-14, cross-checked against all 4 existing 1995 shows and each other
for exact-track duplicates.

Also fixes a real false-positive: "John Mellencamp - Just Another Day" was
matching Jon Secada's unrelated song of the same generic title, because a
perfect title score could carry a middling-but-not-absurd artist-name
coincidence (0.56) over the acceptance threshold. Added a hard artist
similarity floor (0.65) independent of the combined score.

Claude-Session: https://claude.ai/code/session_01L7Rwa6guD5wK8F8tWQwcJX

subwave/broadcasts/tunecaster-rock-1996-07-13.json

@@ -0,0 +1,151 @@
+{
+  "station": "Tunecaster Rock Top 30",
+  "date": "1996-07-13",
+  "tracks": [
+    {
+      "rank": 1,
+      "artist": "Primitive Radio Gods",
+      "title": "Standing Outside A Broken Phone Booth With Money In My Hand"
+    },
+    {
+      "rank": 2,
+      "artist": "Stone Temple Pilots",
+      "title": "Trippin' On A Hole In A Paper Heart"
+    },
+    {
+      "rank": 3,
+      "artist": "Butthole Surfers",
+      "title": "Pepper"
+    },
+    {
+      "rank": 4,
+      "artist": "Metallica",
+      "title": "Until It Sleeps"
+    },
+    {
+      "rank": 5,
+      "artist": "The Smashing Pumpkins",
+      "title": "Tonight, Tonight"
+    },
+    {
+      "rank": 6,
+      "artist": "Garbage",
+      "title": "Stupid Girl"
+    },
+    {
+      "rank": 7,
+      "artist": "Soundgarden",
+      "title": "Burden In My Hand"
+    },
+    {
+      "rank": 8,
+      "artist": "Beck",
+      "title": "Where It's At"
+    },
+    {
+      "rank": 9,
+      "artist": "The Cranberries",
+      "title": "Free To Decide"
+    },
+    {
+      "rank": 10,
+      "artist": "Nada Surf",
+      "title": "Popular"
+    },
+    {
+      "rank": 11,
+      "artist": "Sponge",
+      "title": "Wax Ecstatic (To Sell Angelina)"
+    },
+    {
+      "rank": 12,
+      "artist": "Oasis",
+      "title": "Don't Look Back In Anger"
+    },
+    {
+      "rank": 13,
+      "artist": "Screaming Trees",
+      "title": "All I Know"
+    },
+    {
+      "rank": 14,
+      "artist": "Green Day",
+      "title": "Walking Contradiction"
+    },
+    {
+      "rank": 15,
+      "artist": "Porno For Pyros",
+      "title": "Tahitian Moon"
+    },
+    {
+      "rank": 16,
+      "artist": "The Cure",
+      "title": "Mint Car"
+    },
+    {
+      "rank": 17,
+      "artist": "Goo Goo Dolls",
+      "title": "Long Way Down"
+    },
+    {
+      "rank": 18,
+      "artist": "No Doubt",
+      "title": "Spiderwebs"
+    },
+    {
+      "rank": 19,
+      "artist": "Alice In Chains",
+      "title": "Again"
+    },
+    {
+      "rank": 20,
+      "artist": "The Black Crowes",
+      "title": "Good Friday"
+    },
+    {
+      "rank": 21,
+      "artist": "The Hunger",
+      "title": "Vanishing Cream"
+    },
+    {
+      "rank": 22,
+      "artist": "Alanis Morissette",
+      "title": "You Learn"
+    },
+    {
+      "rank": 23,
+      "artist": "The Wallflowers",
+      "title": "6th Avenue Heartache"
+    },
+    {
+      "rank": 24,
+      "artist": "311",
+      "title": "Down"
+    },
+    {
+      "rank": 25,
+      "artist": "Jewel",
+      "title": "Who Will Save Your Soul"
+    },
+    {
+      "rank": 26,
+      "artist": "Superdrag",
+      "title": "Sucked Out"
+    },
+    {
+      "rank": 27,
+      "artist": "Cracker",
+      "title": "Nothing To Believe In"
+    },
+    {
+      "rank": 28,
+      "artist": "The Hazies",
+      "title": "Skin & Bones"
+    },
+    {
+      "rank": 29,
+      "artist": "Soundgarden",
+      "title": "Pretty Noose"
+    }
+  ]
+}