[Shubham-Padkonde]

Description

Fixes #5092. An integration override such as claude: {} or one with a misspelled evnts key currently acts as events: {}, silently removing every existing event hook during an upgrade.

Treat a missing events field like the other invalid, non-mapping values: warn and preserve the built-in and extension handlers. An explicitly supplied events: {} still disables hooks. This matches the documented override contract and the existing validation comment.

Testing

• Tested locally using this checkout's virtualenv and an offline sample project.
• Ran affected existing tests after uv sync --extra test.

Windows / Python 3.14.6:

• Two regression cases (empty integration entry and misspelled key) fail on the base and pass with this fix. They assert both prior handler layers survive and a warning is logged.
• .venv/Scripts/python -m pytest tests/specify_cli/events -q: 211 passed, 5 skipped, 4 failed. All four failures occur at os.symlink in existing fixture setup because this Windows environment lacks symlink privileges (WinError 1314), before the changed resolver is called. Existing explicit-empty override tests pass. The full repository suite was not run.
• Real CLI sample: initialize an offline Claude project, add an extension event, and run integration upgrade claude --force. Both invalid overrides preserve the generated settings.json hooks unchanged. A subsequent explicit events: {} removes them. The test does not invoke Claude or a live model; it exercises the CLI and generated native configuration.
• git diff --check passes.

AI Disclosure

• I did not use AI assistance for this contribution
• I did use AI assistance

AI disclosure: OpenAI Codex (GPT-6), operating autonomously on behalf of Shubham-Padkonde, investigated the issue, generated the fix and regression tests, ran validation, and drafted this PR. The exact model variant/reasoning setting is not exposed to the agent. No personal line-by-line human review is claimed.