Feature: Extract Social microservice from monolith (MSA step 6)

[Atsilut]

Summary

• Extract friendships, friend requests, and user-blocks into a standalone Social service (social Postgres schema) with public /api/friendships* and /api/users/blocks routes and internal validate/detach APIs.
• Route Chat, Community, Group, and Location social checks through ISocialClient / social-service, and have the monolith delegate user-deletion detach to the new service.
• Remove the monolith Friendships/UserBlocks domains and drop legacy public social tables (no row copy); port coverage to Social.Tests and wire Social into Compose, nginx, CI, and MSA docs.
• Pass explicit subject user ids on internal validate routes (not JWT caller) so invitee/background paths work; run detach in a transaction and map failures to domain exceptions in Api.
• Stabilize Community post/comment list ordering (newest-first posts and user comments; chronological comment trees).

Test plan

• ./scripts/ci/docker-test.sh (or CI social-tests / full ladder) passes
• Local docker compose down -v && docker compose up --build boots social-service and routes /api/friendships* and /api/users/blocks via nginx
• Friend request, accept/ignore/reject, block, and friends-list visibility flows behave as before
• Chat DM/invite/group-room access still enforces friendship and block checks via internal social APIs
• Community and Location mutual-block filtering still goes through social-service
• Group invitation block checks still go through social-service
• User deletion still detaches friendships, requests, and blocks via internal detach endpoint

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