fix: keep failed adaptive actions off frontier

[chubes4]

Summary

• retain failed adaptive action transitions and their post-error observations as bounded diagnostic evidence
• exclude partially reached destinations from replayable states, findings, minimization, revisit accounting, and frontier scheduling
• continue deterministic exploration from the original replayable source and preserve cancellation behavior

Root cause

exploreAdaptiveBrowserStateMachine() captured and registered the post-action DOM state regardless of whether executeAdaptiveAction() completed. For a multi-step action that mutated the page and then failed, the frontier path therefore contained the complete failing action even though only its successful prefix produced the destination. Start-URL resets could never replay that path and repeatedly consumed action and duration budgets.

Replay safety and evidence semantics

WP Codebox does not currently define a partial-step replay contract. This change uses the minimal safe behavior: an action error still produces an error transition with its destination digest, URL/history, mutation novelty, browser observations, and browser_adaptive_action_error diagnostic, but that destination is not registered as a replayable state or queued. Oracle output observed during the failed action remains on the transition rather than becoming a finding with an unreplayable path.

Successful transitions retain the existing state IDs, transition IDs, action ordering, fingerprints, replay paths, and minimization behavior. Authored and one-shot browser modes are unchanged.

Budget and cancellation effects

A partially failed action consumes one action/error as before, but it cannot create repeated reset/replay failures or spend the remaining duration budget on a known-unreplayable source. Other candidates continue from the same replayable source under start-URL reset. Cancellation after a partial failure retains the error transition and terminates with the existing cancelled summary/diagnostic semantics.

Tests

Passed:

• npx tsx tests/browser-adaptive-exploration.test.ts (9 tests, including intercepted two-click overlay failure, continued valid exploration, no reset loop, cancellation, minimization exclusion, and deterministic output)
• npx tsx tests/browser-action-corpus.test.ts (5 tests)
• npx tsx tests/adversarial-recipe-orchestration.test.ts
• npx tsx tests/schema-parity.test.ts
• npx tsx tests/runtime-contract-package-exports.test.ts
• npm run build
• git diff --check

npm run check passed production-boundary enforcement, build, and the preceding smoke commands, then stopped at the unchanged known #1745 failure: wordpress.collect-workload-result outputShape should mention outputSchema id. The implicated command registry and smoke files are unchanged from origin/main.

Fixes #2031