developer_float_migrate: make both methods actually run

The Proximity wrangle read sample_dist, sample_rad and speed and the
Connectivity wrangle read depth and haste; none exist on the interface,
so every channel was zero and the node was a no-op. They now read
prox_dist, radius, infl and connect_depth. Proximity also read a detail
attribute named len while the edge-length promote writes __len.

Connectivity referenced undefined variables (dir_val, input_attr),
divided by zero on an empty sample set, which failed the whole solver
cook, and wrote a leftover debug array attribute. Both methods now
leave the value alone when nothing is sampled.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

 .../sop_lsgalante.developer_float_migrate.1.1.hdalc | Bin 13289 -> 13530 bytes
 1 file changed, 0 insertions(+), 0 deletions(-)

diff --git a/otls/sop_lsgalante.developer_float_migrate.1.1.hdalc b/otls/sop_lsgalante.developer_float_migrate.1.1.hdalc
index 6790ce3..8f5b928 100644
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