test(e2e): re-point Tier-C kiln seam from resolved #364 to live kiln#375 (#297)

[avrabe]

What

Re-points the Tier-C meld→kiln execution test (tier_c_fused_executes_on_kiln, #297) from the now-closed kiln#364 to the live blocker kiln#375, with the accurate current root cause. Test-annotation only — no logic change; the test stays #[ignore]d.

Why

kiln#364 (kilnd required a core-instance _start) was resolved by kiln#374 (wasi:cli/run canonical entry). I verified against a freshly-built post-#374 kilnd:

• ✅ unfused original command component now runs on kilnd (the _start gate is gone).
• ❌ meld-fused --component fails one layer deeper:
  [ComponentRuntime][E5DC2] wasi:cli/run export references an out-of-bounds component instance index.

Attribution (differential oracle): the same fused artifact runs correctly on wasmtime 41 (Hello wasm component world from C!, exit 0). Same bytes, wasmtime accepts / kilnd rejects ⇒ meld's output is spec-valid; the defect is in kilnd's component-instance resolution for a multi-core-module fused component. Grounded reproduction filed on kiln#375 (E5DC2 flagged as possibly distinct/earlier than its user-import linking layer).

Leaving the stale blocked on kiln#364 annotation would mislead a future reader into un-ignoring a test that now fails for a different, still-open reason. This fixes the pointer and records the exact E5DC2 root cause + the wasmtime-proven attribution in the docstring.

Verification

• cargo test -p meld-core --test golden_e2e --no-run — compiles clean.
• Pre-commit gate green: fmt, clippy, cargo-test all passed.
• Test remains #[ignore]d; it un-ignores and pins the seam green when kiln#375 lands.

Refs #297, kiln#375, kiln#364.

🤖 Generated with Claude Code

[github-actions]

LS-N verification gate

✅ 58/58 approved LS entries verified

	count
Passed (≥1 test, all green)	58
Failed (≥1 test failure)	0
Missing (no ls_*_NN_* test found)	0

_{Approved loss-scenarios.yaml entries are expected to have a
regression test named ls_<letter>_<num>_* (e.g. LS-A-11 →
ls_a_11_*). The gate runs each prefix via cargo test --lib --no-fail-fast and aggregates pass/fail/missing.}

Failed LS entries

(none)

Missing regression tests

(none)

_{Updated automatically by tools/post_verification_comment.py.
Source of truth: safety/stpa/loss-scenarios.yaml.}