feat: ship unified design and workspace analytics together

[paulocastellano]

Summary

• Bring the TryPost Connect visual language into TryPost, including the rounded app shell, shared page headers, and unified Posts list and calendar navigation.
• Add workspace analytics with daily follower snapshots, publication history backfill, persisted post metrics, dashboard charts, publication details, and API/MCP access.
• Integrate both efforts with the current main, preserving the latest YouTube description and Instagram original image behavior.

This PR supersedes #370 so the design and analytics work can be reviewed and shipped together.

Validation

• npm run build and ./node_modules/.bin/vue-tsc --noEmit passed on the combined branch.
• vendor/bin/pint --dirty --format agent passed.
• php artisan test --compact tests/Feature/Analytics — 212 passed (1,066 assertions).
• php artisan test --compact tests/Feature/PostControllerTest.php — 86 passed (447 assertions).
• php artisan test --compact tests/Feature/UiComponentDesignTest.php — 38 passed (177 assertions).
• Browser tests for workspace analytics, publication analytics, post details, Instagram media choices, and YouTube descriptions passed.