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- docs: remove outdated Installation/Administration files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/config/main.yml

@@ -18,18 +18,39 @@ server:
 docker:
   services:
     redis:
-      enabled: true
+      enabled:            true
+      cpus:               "0.3"
+      mem_reservation:    "256m"
+      mem_limit:          "512m"
+      pids_limit:         256
     database: 
-      enabled: true
+      enabled:            true
+      cpus:               "1.0"
+      mem_reservation:    "2g"
+      mem_limit:          "3g"
+      pids_limit:         512
     mastodon: 
-      image:            "ghcr.io/mastodon/mastodon"
-      version:          latest
+      image:              "ghcr.io/mastodon/mastodon"
+      version:            latest
       backup:
         no_stop_required: true
-      name:             "mastodon"
+      name:               "mastodon"
+      cpus:               "1.0"
+      mem_reservation:    "1.5g"
+      mem_limit:          "2g"
+      pids_limit:         512
     streaming: 
-      image:            "ghcr.io/mastodon/mastodon-streaming"
-      version:          latest
-      name:             "mastodon-streaming"
+      image:              "ghcr.io/mastodon/mastodon-streaming"
+      version:            latest
+      name:               "mastodon-streaming"
+      cpus:               "0.3"
+      mem_reservation:    "256m"
+      mem_limit:          "512m"
+      pids_limit:         256
+    sidekiq:
+      cpus:               "0.8"
+      mem_reservation:    "1g"
+      mem_limit:          "1.5g"
+      pids_limit:         512
   volumes:
-    data:               "mastodon_data"
+    data:                 "mastodon_data"