fix(plugin): resolve local package manifest entrypoints - #53796

Issue for this PR

Addresses #52300 (local package-directory manifest entrypoint discovery). Direct file-path configuration is unchanged; that separate part of the issue is not claimed fixed.

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Resolve local plugin directories through their package manifest before asking the runtime to resolve the resulting entrypoint. Packages using main: dist/index.js or conditional exports then load when configured by their directory.

Use [email protected] for conditional maps. Respect deliberately unexported server/TUI/RPC files, reread manifests during reload, and retain the configuration layer's real-path containment checks. No API contract changes or generated client edits.

How did you verify your code works?

Prior verification for candidate 5e7a5194045ed39589779bd8a7160dadb18cb071, baseline 5183ea45c39aaabf14236d0ce8ae0b086d9c31e8:

• bun run check: all 36 tasks passed in a bounded 10 GiB scope.
• Plugin package tests: 14 passed.
• Focused core supervisor reload/containment tests passed through the package's isolated test runner.
• Built the single-platform CLI with --skip-install --skip-web-ui. Independently packed/installed Claude and Jev plugins loaded directly from their package directories and passed direct/routed shared-backend streaming, concurrent-project reload and real read-tool continuation fixtures.

These are the original candidate's offline receipts, not current-live-target hosted acceptance. Current full-candidate Codex review and required application CI remain outstanding. Actual subscription inference is outside the offline tests. No local tests or builds were run during this maintenance pass.

Screenshots / recordings

Not applicable: package loading change with no UI changes.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR