#327 asdf:load-system "alexandria" via central-registry push + source-compile hangs (infinite loop)

Repro (from repo root, any build/funcl with asdf loaded):

(load "asdf.lisp")
(push #p"ocicl/alexandria-20240503-8514d8e/" asdf:*central-registry*)
(asdf:load-system "alexandria")

funcl spins at 99% CPU indefinitely (observed 30 min, ~2.1GB RSS, not OOM). Gets into ALEXANDRIA-2 source-compile (errors "not a byte-vector" in float deftypes / %deftype-register, "(RES) is not a SYMBOL" in DEFPACKAGE ALEXANDRIA-2) and then loops.

Pre-existing: reproduced on baseline (before the cave#321 B1 seam), so not a regression. Discovered while gating #321.

The VALIDATED north-star path — (asdf:load-system "alexandria") via the FASL replay (cave#309) / ocicl.csv registry — is unaffected; this is the central-registry-push source-compile route hitting float/deftype gaps then spinning. Two things worth separating: (a) why it LOOPS rather than erroring out (the more important bug), (b) the underlying float-deftype / compile-file gaps.

Related: #318 (dynamic-linking epic; asdf gate should use the FASL path, not this route).