Add social-sync manifest and metadata to personal-brand booster

[vepretski]

Motivation

• Ensure generated platform assets for the 7ya personal-brand booster can be synchronized across all target social channels by embedding sync metadata and producing a single manifest and checklist.
• Provide machine-verifiable validation that every generated file includes canonical CTA and platform sync fields so cross-posting and UTM tracking remain consistent.

Description

• Extend script/personal-brand-booster.ts to compute a campaign_id and emit per-platform metadata (platform_key, sync_status, sync_key, cross_post_group, canonical_url, utm_url) into each generated markdown file.
• Generate social-sync-manifest.json and social-sync-checklist.md that list all generated platform assets with their sync metadata and cadence.
• Add sync-aware validation to validation.json so it verifies the manifest coverage, platform ready statuses, and that every platform file contains the required sync and CTA fields.
• Update the spec and schema files (project/ops/docs/PERSONAL_BRAND_BOOSTER_MVP_SPEC.md and project/ops/docs/PERSONAL_BRAND_BOOSTER_OUTPUT_SCHEMA.json) to document the Social Sync Contract and require sync_policy and sync validation fields, and regenerate the YB-2026 output bundle under outputs/personal-brand-booster-yb-2026.

Testing

• Ran bun run personal-brand:boost --source ./input/igor-vepretski-yisrael-beiteinu-campaign.md --lang both --out ./outputs/personal-brand-booster-yb-2026 and confirmed the tool produced the expected artifacts including social-sync-manifest.json and social-sync-checklist.md (run succeeded).
• Ran bunx prettier --check against script/personal-brand-booster.ts, the updated spec/schema, and the generated manifest/checklist/validation files and fixed formatting issues; the final --check passed.
• Ran repository checks (git diff --check) and validation generation, and observed validation.json reports a passing sync status (has_manifest, all_platforms_ready, all_platform_files_valid).

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Codex Task