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/settings.toml.example

@@ -8,9 +8,16 @@ transcript_days = 30
 document_days = 0
 
 [whisper]
+# Active when ASR_BACKEND=whisper (default).
 url = "http://localhost:9000"
 timeout_seconds = 120
 
+[canary]
+# Active when ASR_BACKEND=canary. Both blocks are always loaded; the
+# server reads only the one matching the env-selected backend.
+url = "http://minerva.lan:9002"
+timeout_seconds = 180
+
 [ollama]
 url = "http://localhost:11434"
 model = "gemma3:4b"