[Copilot]

Summary

Fixes all ESLint errors in src/Poster.ts, migrates the ESLint configuration to the modern flat-config format (required by ESLint v10), and exports the new PostResult interface so the changes remain non-breaking for TypeScript consumers.

Changes

ESLint migration

• Replaced .eslintrc.json + .eslintignore with eslint.config.js (flat config) using @typescript-eslint/eslint-plugin's flat/recommended preset

src/Poster.ts type improvements

• Introduced PostResult interface (now exported) replacing {[key: string]: any} / GeneralObject<any> across all post, repost, and reply overload signatures
• Typed blurhash pixel arrays as number[] instead of any[]
• Fixed Mastodon image attachment to use masto.js's properly-typed camelCase field (mediaIds) instead of bypassing types with snake_case media_ids + as any
• catch (e) {} → catch {} in three empty catch blocks
• Merged let imageKey declaration + assignment into const imageKey = randomUUID()
• Removed unused UUID and GeneralObject imports

Non-breaking fix

PostResult is now exported from both src/Poster.ts and src/index.ts. Consumers can import it directly:

import { PostResult } from 'social-media-manager';