fix(doctest): detect a crashed lez_core instead of passing silently

[dlipicar]

The blind spot

"Confirm the module is loaded" asserted the bare substring '"status":"loaded"'. capability_module is always loaded and satisfies that substring on its own, so a lez_core that loaded and then crashed still passed the step. The failure only surfaced several steps later at the first call, as a bare RPC_FAILED with nothing explaining why.

That is exactly what the nightly has been showing on both platforms (run):

load-module  -> {"module":"lez_core","status":"ok","version":"0.3.0"}
status       -> {"name":"lez_core","status":"not_loaded", ...}   ← PASSED
module-info  -> {"name":"lez_core","status":"not_loaded", ...}   ← PASSED
call name    -> {"code":"RPC_FAILED", ...}                       ← first red

What this PR does

• Match lez_core's own entry ("name":"lez_core","status":"loaded") so the step fails where the problem actually is.
• Add a cat logs.txt right after loading. When a module subprocess dies, the host writes the dlopen error and Module process crashed there — and the spec only ever cat'ed the log before loading, so CI never captured the reason.

What it does not do

This makes the failure legible; it does not fix the underlying crash.

The crash is a missing shared-library dependency. An .lgx is a gzipped tar, so Nix's reference scanner sees no store paths inside it and records an empty closure for the .lgx derivation. A cache-substituted .lgx therefore arrives without the store paths its binaries dlopen() — for lez_core that is wallet_ffi's pyo3 → libpython3.13. Cache miss (built locally) = green, cache hit = dead module, which is why this looked like a ~1/3 flake for months.

Fix in flight as logos-co/nix-bundle-lgx#7 (verified against logos-storage-module, which hits the same defect via libcxx-16.0.6 on macOS). Once that lands and this module re-pins, the crash should go away — and with this PR, if it doesn't, CI will say why.

🤖 Generated with Claude Code

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