fix(makefile): extract inline Python to script to fix parse error

The multi-line python3 -c heredoc in the Makefile caused
"missing separator" errors since Make runs each recipe line
in a separate shell. Moved to web/scripts/init_landing_seeds.py.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/scripts/init_landing_seeds.py

@@ -0,0 +1,22 @@
+"""Create minimal seed files for SQLMesh staging models that require landing data."""
+import gzip
+import json
+from pathlib import Path
+
+seed = {
+    "date": "1970-01-01",
+    "captured_at_utc": "1970-01-01T00:00:00Z",
+    "venue_count": 0,
+    "venues_errored": 0,
+    "venues": [],
+}
+morning = Path("data/landing/playtomic/1970/01/availability_1970-01-01.json.gz")
+recheck = Path("data/landing/playtomic/1970/01/availability_1970-01-01_recheck_00.json.gz")
+morning.parent.mkdir(parents=True, exist_ok=True)
+for p in [morning, recheck]:
+    if not p.exists():
+        with gzip.open(p, "wt") as f:
+            json.dump(seed, f)
+        print("created", p)
+    else:
+        print("exists ", p)