feat(library): expand advanced library cli surface

[dogbertdev]

Summary

• expand the library CLI with nested section, refresh, item, subtitle, artwork, detect, discover, person, and media command families
• add a dedicated library service layer that uses a hybrid plexgo SDK plus handwritten request strategy for dynamic Plex endpoints
• cover live Plex compatibility gaps found during smoke testing, including subtitle upload title defaults, flat prefs encoding, stream delete/offset fallbacks, string marker types, direct asset-path file downloads, and clearer unavailable-resource errors
• add command and service tests plus update the README and library coverage docs

Testing

• go test ./...
• live smoke tests against a Plex server for section create/edit/delete, item edit/refresh/analyze, prefs updates, subtitle upload, stream get/delete/offset, artwork get/set/update, marker create/edit/delete, chapter-image, media part download, detect credits/voice/bif, discovery reads, person reads, and intro detection on season targets

Notes

• intro detection appears to be season-scoped on the tested Plex server, so the docs/examples now use season metadata IDs
• some Plex endpoints remain resource-dependent rather than universally available, such as loudness/levels and BIF assets

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 9da1ce97f4

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[dogbertdev]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 7e23b8d556

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[dogbertdev]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 65c8af11cb

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".