feat: independent social posts, workspace analytics and media editing

[paulocastellano]

Summary

• Create and edit one post per social account, with independent content, media, settings, scheduling, and notes in the shared composer.
• Add workspace analytics with follower snapshots, publication backfill, persisted metrics, dashboard reports, and API/MCP access.
• Integrate current main, including YouTube Shorts descriptions and Instagram original image ratios, into the independent-post composer.
• Put Instagram publication type and image ratio with the format controls at the top of the composer. Detect unsupported original image ratios per slide and offer a crop action.
• Add per-image media editing with crop presets, alt text, appearance filters, and brightness, contrast, saturation, and warmth adjustments. Applying appearance alone preserves the image dimensions.

This PR supersedes #373 and #370. The work is based on codex/independent-social-posts.

Validation

• npm run build, vue-tsc --noEmit, and ESLint passed.
• vendor/bin/pint --dirty --format agent passed.
• Analytics, post-controller, AI creation, post-update, YouTube description, PostHog, and billing feature tests passed.
• Browser tests for workspace analytics, post details, Instagram media choices, YouTube descriptions, composer crop, image cropper, and channel media issues passed.