Preserve plugin app manifest order

[charlesgong-openai]

Summary

• Preserve app declaration order when loading plugin .app.json files.
• Keep plugin connector summaries in plugin app order after connector metadata is merged and filtered.
• Add regression coverage for .app.json order and connector summary order.

Validation

• just fmt
• just test -p codex-chatgpt connectors_for_plugin_apps_returns_only_requested_plugin_apps
• just test -p codex-core-plugins effective_apps_preserves_app_config_order
• just fix -p codex-core-plugins (passes with existing clippy large_enum_variant warning in core-plugins/src/manifest.rs)
• just fix -p codex-chatgpt
• just bazel-lock-update
• just bazel-lock-check

[github-actions]

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[charlesgong-openai]

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