harness: recognize verified Wasmtime trap diagnostics

[lannbot]

Summary

• Add seven source-verified trap diagnostic mappings in the existing harness matcher: named backpressure-counter range errors, already-delivered subtask cancellation, synchronous operations on joined waitables, stream terminal-state wording, intra-component nonnumeric copy restrictions, and bare Wasmtime core-unreachable wording.
• Add positive and negative matcher tests. Do not equate generic overflow/underflow, deadlock/cannot-block, exception/unreachable, or the future-write diagnostic combining prior success with peer drop.
• Remove only the 26 Wasmtime expected failures proven to pass after normalization. Runtime behavior and messages remain unchanged.

Verification

• Independent review: LGTM, matching runtime/spec/Wasmtime call sites and exact removed rows.
• Full just gates < /dev/null passed. Log /tmp/opencode/diagnostic-equivalence-gates.log.
• Supplementary Wasmtime FIFO and seed1:570 passed,102 known failures (25 diagnostic mismatches),4 skips,174 excluded commands,0 unexpected results. Public guest tests3passed per mode.
• Official conformance unchanged:1286 passed commands,125xfail,95pending-runtime,5unsupported directives; no unexpected results. Runtime1037passed/3existingignored, seeded1034passed/6existingignored.
• Required shell/browser/OPFS, packaging and available consumer smokes passed; consumer statuses unchanged. Existing JSC arm64 unavailability and deferred/profile/optional-fixture exclusions remain.

No manifests, runtime code, protocol, or goldens changed. Automerge will be armed and watched through merge.