chore: rename mclogs filenames, asset paths, and runtime identifiers

Two file renames (docker/mclogs.ini -> docker/iblogs.ini,
web/public/css/mclogs.css -> web/public/css/iblogs.css) plus the
internal references that pointed at them (Dockerfile COPY directive,
the linux user name in the container).

Also catches the runtime identifier renames: env-var prefix MCLOGS_*
-> IBLOGS_* (compose files), browser cookie name MCLOGS_SETTINGS ->
IBLOGS_SETTINGS (web/public/js/log.js), production image tag
ghcr.io/aternosorg/mclogs:2 -> ghcr.io/indifferentketchup/iblogs:2,
and the README walk-through with the new branding.

example.config.json branding strings (legal contact, mclo.gs frontend
name) and visible UI text (taglines, meta descriptions) are deferred
to a separate branding commit.

dev/compose.yaml

@@ -1,11 +1,11 @@
-name: "mclogs"
+name: "iblogs"
 services:
   web:
     build:
       context: ..
       dockerfile: ./Dockerfile
     environment:
-      - MCLOGS_WORKER_REQUESTS=1
+      - IBLOGS_WORKER_REQUESTS=1
       - FRANKENPHP_WORKERS=4
     ports:
       - "80:80"