feat(whisper): feed profile_terms into initial_prompt at decode time

Previously profile_terms only reached the LLM cleanup stage as the
dictionary_terms suffix. Whisper decoded without any vocabulary hint, so
domain names ('Wren', 'CORBEL') were misspelled on the first pass and the
LLM had to guess at the correction.

build_initial_prompt (src-tauri/src/commands/mod.rs) collapses caller /
profile / terms into a single Whisper prompt:
  caller_prompt > profile_prompt + "Vocabulary: <terms>." > None

transcribe_pcm, transcribe_file, and start_live_transcription_session all
route through the helper, so the three paths stay in lockstep.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src-tauri/src/commands/live.rs

@@ -12,6 +12,7 @@ use serde::{Deserialize, Serialize};
 use tauri::ipc::Channel;
 
 use crate::commands::audio::persist_audio_samples;
+use crate::commands::build_initial_prompt;
 use crate::commands::models::{default_model_id_for_engine, ensure_model_loaded};
 use crate::AppState;
 use kon_ai_formatting::{post_process_segments, FormatMode, PostProcessOptions};
@@ -214,16 +215,13 @@ pub async fn start_live_transcription_session(
 
     // Collapse the effective initial_prompt on the struct so downstream
     // `TranscriptionOptions` construction (see `maybe_dispatch_chunk`) picks
-    // up profile fallback without further plumbing.
-    let effective_prompt = match config.initial_prompt.as_deref() {
-        Some(p) if !p.is_empty() => p.to_string(),
-        _ => profile.initial_prompt.clone(),
-    };
-    config.initial_prompt = if effective_prompt.is_empty() {
-        None
-    } else {
-        Some(effective_prompt)
-    };
+    // up profile fallback + vocabulary injection without further plumbing.
+    let request_prompt = config.initial_prompt.clone().unwrap_or_default();
+    config.initial_prompt = build_initial_prompt(
+        &request_prompt,
+        &profile.initial_prompt,
+        &profile_terms,
+    );
 
     let model_id = config
         .model_id