[runtime] stabilize schema verify polling test

[GsCommand]

Motivation

• The full-chain schema verification step was intermittently aborting in CI because the test used a too-short timeout and only a single quick retry, which doesn't respect the runtime validator warmup model.
• The goal is to make the test deterministic in CI without changing runtime code by making the verify helper more tolerant and by polling the verify endpoint a few times.

Description

• Increased the /verify?schema=1 request helper AbortController timeout from 5000 ms to 10000 ms by updating verifyReceiptWithTimeout in runtime/tests/runtime-signing.test.mjs.
• Replaced the previous single-retry flow with a polling loop that allows up to 3 attempts, logs each attempt with console.log messages like [chain] before verify request attempt N and [chain] after verify response attempt N, and stops early if a 200 response is observed.
• When a 202 is returned the loop logs the warmup response and waits for the retry_after_ms value if present, otherwise falls back to 1200 ms before retrying.
• Preserved the original chain-step logs for clean/summarize/classify and kept the final schema/hash/signature assertions unchanged, while improving failure messages to include the last status/body and any abort details.

Testing

• Ran the modified test file with node --test runtime/tests/runtime-signing.test.mjs and the suite passed (all subtests succeeded).

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Codex Task