feat(pipeline): per-clip-pair morph manifest + member-pair baking (154 clips)

Tasks 1-2 of the altitude clip-pair morph plan. Manifest emits a morph
entry for every video pair in adjacent altitudes, both directions
(<src>__<dst>.mp4 zoom-in + .rev zoom-out); generate_media() bakes them
all via the existing xfade=zoomin recipe keyed by clip member.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_build_pool_manifest.py

@@ -0,0 +1,56 @@
+"""Tests for the hand-authored rotating-pool manifest builder
+(simulator/build_pool_manifest.py) — the per-clip-pair morph model."""
+
+import simulator.build_pool_manifest as b
+
+
+def _expected_pairs():
+    """Every adjacent (higher H, lower L) edge, every member pair, BOTH directions."""
+    order = b.RING_ORDER
+    n = len(order)
+    expected = set()
+    for i in range(n):
+        H, L = order[i], order[(i + 1) % n]
+        for h in b.POOLS[H]:
+            for l in b.POOLS[L]:
+                expected.add((h, l, f"transitions/{h}__{l}.mp4"))       # zoom in
+                expected.add((l, h, f"transitions/{h}__{l}.rev.mp4"))   # zoom out
+    return expected
+
+
+def test_transitions_are_per_clip_pair_both_directions():
+    m = b.build_manifest()
+    trans = m["ring"]["transitions"]
+    expected = _expected_pairs()
+    got = {(t["from"], t["to"], t["file"]) for t in trans}
+    assert got == expected
+    assert len(trans) == len(expected) == 154
+    assert all(t["model"] == "placeholder-zoom" for t in trans)
+
+
+def test_generate_media_bakes_every_member_pair(monkeypatch, tmp_path):
+    calls = []
+
+    def fake_run(args, **kw):
+        out = args[-1]
+        from pathlib import Path
+        Path(out).parent.mkdir(parents=True, exist_ok=True)
+        Path(out).write_bytes(b"x")
+        calls.append(str(out))
+
+        class R:
+            returncode = 0
+
+        return R()
+
+    monkeypatch.setattr(b, "MEDIA", tmp_path)
+    monkeypatch.setattr(b.subprocess, "run", fake_run)
+    monkeypatch.setattr(b, "_ffmpeg", lambda: "ffmpeg")
+    b.generate_media()
+    outs = {c.split("transitions/")[-1] for c in calls}
+    fwd = {f"{h}__{l}.mp4" for H, L in b._adjacent_edges()
+           for h in b.POOLS[H] for l in b.POOLS[L]}
+    rev = {f"{h}__{l}.rev.mp4" for H, L in b._adjacent_edges()
+           for h in b.POOLS[H] for l in b.POOLS[L]}
+    assert fwd <= outs and rev <= outs
+    assert len(fwd) + len(rev) == 154