fix(plot): no-floor route2 deploy panel was blank -- hk_abl column present but all-nan

The plotter picked hk_abl (dense proxy) whenever the COLUMN existed, but no-floor
runs (rollout_ablate_frac=0) emit hk_abl as 0/0 -> all-nan, so the deploy panel
came up empty. Test for finite data (_has_data) not column presence; fall back to
the sparse-but-real hk_dep (every eval_ablate_every steps). _ema carries values
across the nan gaps -> a held step-line.

Co-Authored-By: Claudypoo <288921227+claudypoo@users.noreply.github.com>

docs/figs/dyn_sub4.png

@@ -0,0 +1 @@
+../../out/figs/dyn_sub4.png

docs/figs/dyn_sub4_hack_overlay.png

@@ -0,0 +1 @@
+../../out/figs/dyn_sub4_hack_overlay.png

scripts/plot_dynamics.py

@@ -128,12 +128,16 @@ def parse_log(path: Path) -> dict | None:
     # under the hack_s/gt_s keys -> all downstream (panels, onset, overlay) reads
     # it. Prefer the DENSE per-step proxy (hk_abl, every step) over the sparse
     # held-out eval (hk_dep, every eval_ablate_every steps); fall back to hk_dep
-    # for older runs that predate the proxy.
+    # when hk_abl carries no data. No-floor runs (rollout_ablate_frac=0) have the
+    # hk_abl COLUMN present but every cell is "0/0" -> all-nan, so test for finite
+    # values, not mere column presence, else the deploy panel comes up blank.
+    def _has_data(key):
+        return key in run and np.isfinite(run[key]).any()
     if arm in ("routing", "routing2"):
-        if "hk_abl" in run:
+        if _has_data("hk_abl"):
             run["hack_s"] = run["hk_abl"]
             run["gt_s"] = run["slv_abl"]
-        elif "hk_dep" in run:
+        elif _has_data("hk_dep"):
             run["hack_s"] = run["hk_dep"]
             run["gt_s"] = run["slv_dep"]
     return run