mastodon: tighten resources, robust exec tasks, and env defaults

- resources: per-service cpus/mem/pids for mastodon/streaming/sidekiq/redis/db
- compose: rename service key to "mastodon" (was: web), set service_name blocks
- tasks(01_setup): run rails db:migrate via docker exec (non-tty, login shell)
- tasks(02_administrator): healthchecks for 'mastodon', sed with absolute path,
  tootctl as user 'mastodon' (non-tty), optional re-health wait
- env.j2: add RAILS_ENV={{ ENVIRONMENT | default('production') }}
- resource.yml.j2: fix get_app_conf path (service_name default spacing)
- docs: remove outdated Installation/Administration files

Context: https://chatgpt.com/share/68d332a0-ae98-800f-b418-c0d0262eaa2e

roles/web-app-mastodon/README.md

@@ -8,12 +8,6 @@ Dive into a decentralized social experience with Mastodon, a vibrant platform th
 
 This role deploys Mastodon using Docker, streamlining the installation and configuration of a full-featured social networking platform. Mastodon is built to support federation across multiple instances, offering robust content moderation, real-time updates, and flexible API integrations. Its advanced architecture—including separate services for the web frontend, streaming API, and background job processing—ensures high performance and scalability for large communities.
 
-For detailed configuration and operational instructions, please refer to the following files in this directory:
-- [Installation.md](./Installation.md)
-- [Administration.md](./Administration.md)
-- [Upgrade.md](./Upgrade.md)
-- [User_Administration.md](./User_Administration.md)
-
 ## Features
 
 - **Decentralized Network:** Connect with users across multiple instances in a federated social media ecosystem.