Fix repository-wide ESLint baseline

[chubes4]

Problem

Running the repository ESLint command currently fails across unrelated existing source files:

npx wp-scripts lint-js

Observed while verifying #160 on 2026-08-04: 921 problems (917 errors, 4 warnings), including Prettier drift, missing JSDoc params, and TypeScript lint violations across Compose, Transcribe, Socials, and other existing files.

Expected

The repository-wide ESLint command passes so feature PRs can use it as a meaningful deterministic gate.

Scope

• Normalize existing source to the configured WordPress formatting rules.
• Fix substantive lint findings rather than disabling rules globally.
• Add an explicit package script or CI gate for the canonical lint command.
• Keep cleanup separate from feature work such as Use shared exact date ranges in Network analytics #160.