fix(core): compare Codex GPT versions by major and minor

[rekram1-node]

Ports the Codex OAuth model filter fixes from dev (#47384, #47385).

The filter matched /^gpt-(\d+\.\d+)/ and parseFloat-ed the prefix, so:

• integer version ids like gpt-6-astra / gpt-6 were not admitted at all
• parseFloat also misranked future versions (gpt-5.10 → 5.1 < 5.4)

Now the match captures the major and minor separately and compares them numerically:

const match = apiID.match(/^gpt-(\d+)(?:\.(\d+))?/)
const major = Number(match?.[1])
const minor = Number(match?.[2] ?? 0)
// admitted when major > 5 || (major === 5 && minor > 4)

The explicit allowlist/disallowlist entries (codexAllowed, codexDisallowed, including gpt-5.5-pro and gpt-5.6) still take precedence, so older-model blacklisting behavior is unchanged.

Extends provider-openai.test.ts with gpt-6-astra, gpt-5.10, gpt-5, gpt-5.04-astra, and gpt-4.99 cases mirroring the dev test suite.