Refactor: Remove unused Whisper variants

This commit removes the `whisper_variant` and `whisper_hotwords_variant`
fields from the `run_id` generation and the `print_meta_summary`
function.

These variants are no longer used as the project is shifting focus to
LLM-based generation. The `run_full_case.rs` example has also been
updated to reflect this change.

server/.env.example

@@ -17,6 +17,13 @@ SESSION_TIMEOUT_HOURS=8
 # Set to false for plain-HTTP local dev; browsers refuse Secure cookies on http://
 COOKIE_SECURE=true
 
+# ASR backend: 'whisper' (default, whisper-asr-webservice) or 'canary'
+# (NeMo Canary container, see docs/canary.md). A switch requires a
+# server restart and the OTHER backend's container must be stopped on
+# the GPU host — Whisper + Canary together exceed the 12 GB VRAM budget
+# of the RTX 3060 (see docs/canary.md §2.6).
+ASR_BACKEND=whisper
+
 # Optional filesystem resources (uncomment if used)
 # VOCAB_DIR=./vocab
 # HUNSPELL_DICT=/usr/share/hunspell/de_DE.dic