fix: meet the portal's listing rules for the subtitle and the support URL

[sherwinski]

One Line Summary

.codex-plugin/plugin.json now has a 27-character subtitle and a supportURL, and the packager gate checks both rules, so the OpenAI plugin directory draft can go to review.

Motivation

The 1.2.2 draft uploaded (the name and MCP checks passed) and the portal reported 2 blocking findings on the metadata:

• "Subtitle must be 30 characters or fewer." The subtitle was "Set up and send push notifications" (34 characters).
• "Support URL is required."

It also reported 2 advisory findings: "Remove or revise promises and guarantees that the plugin's functionality does not support" and "Remove pricing, subscription offers, and temporary promotions from the description." The long description said "market leading" and "A free OneSignal account".

Scope

• .codex-plugin/plugin.json:
  • shortDescription: "Set up push, email, and SMS" (27 characters). This keeps the intent of PR docs: name push, email, and SMS in the plugin descriptions #70, whose 36-character subtitle would fail the same check.
  • supportURL: https://github.com/OneSignal/onesignal-agent-plugin/issues, the same URL the Claude manifest uses for supportUrl.
  • longDescription: "the market leading customer engagement solution" is now "a customer engagement platform"; "A free OneSignal account" is now "A OneSignal account".
• scripts/package_directory_bundle.py: the source gate checks displayName and shortDescription at 30 characters (SUBMISSION_TEXT_LIMITS) and requires the 4 listing URLs as HTTPS (LISTING_URL_FIELDS). 2 new self-test cases cover a long subtitle and a missing support URL.
• No changes to skills, references, templates, .mcp.json, or the Claude manifest.
• No version bump; the release PR bumps the version.

Testing

• python3 -m json.tool .codex-plugin/plugin.json parsed with no errors.
• python3 -m py_compile scripts/*.py passed.
• python3 scripts/package_directory_bundle.py --check printed bundle check passed (version 1.2.2; nothing written).
• python3 scripts/package_directory_bundle.py --self-test passed all 19 cases, including the 2 new ones.
• Not tested: the portal upload. The 2 blocking findings quote exact rules, so I expect them to clear. The 2 advisory findings come from a text review, so the portal may still flag other phrases.

Affected code

• Skills
• Scripts
• References
• Templates
• Manifests

Checklist

• Commit subjects use conventional prefixes
• Bundle gate passes
• No secrets in the diff