feat: OpenWhispr-inspired transcription polish pass

Major quality pass on top of Phase 2. Five substantive changes plus
cross-cutting touches across audio, hotkey, transcription, and Tauri
command layers.

  Transcription quality

  - Long-audio chunking in commands/transcription.rs: Parakeet and large
    file transcription now chunk-and-recompose with overlap trimming, so
    the live-path chunking advantage extends to file-based workflows.
  - Stateful live speech gate in commands/live.rs on top of the earlier
    duplicate-boundary filtering — distinguishes start-of-speech from
    mid-speech and holds state across chunks.

  Auto-learning corrections

  - New crates/ai-formatting/src/correction_learning.rs: extracts user
    text corrections from viewer edits and proposes additions to the
    active profile's vocabulary.
  - src-tauri/src/commands/profiles.rs bridge for frontend-driven
    confirmation of learned terms.
  - src/routes/viewer/+page.svelte hooks the learning path into the
    segment-edit flow so corrections feed profile_terms without a
    separate 'train this profile' UX.

  Transcript profile provenance

  - Migration v8 (crates/storage/src/migrations.rs) adds profile_id to
    transcripts, defaulting to DEFAULT_PROFILE_ID so existing rows stay
    valid.
  - crates/storage/src/database.rs: TranscriptRow + CRUD carry profile_id.
  - src-tauri/src/commands/transcripts.rs: add_transcript accepts and
    persists profile_id.
  - DictationPage.svelte + FilesPage.svelte send activeProfileId on
    capture so learned corrections are attributed to the right profile.

  Cleanup prompt contract

  - crates/ai-formatting/src/llm_client.rs hardened: the CLEANUP_PROMPT
    now specifies concrete do/do-not rules, ready for a real model-backed
    cleanup pass. The llm_client is still a stub — kon-llm remains unwired
    — but the prompt shape is final.

  Cross-cutting polish

  - Minor touches in audio (capture/decode/resample), hotkey (lib/linux/stub),
    core, transcription (concurrency/model_manager/local_engine/whisper_rs),
    and the rest of src-tauri/src/commands/*: error-path tightening, log
    clarity, TS-migration follow-ups (@ts-nocheck additions for incremental
    typing).

Verified locally: npm run check, cargo test -p kon-ai-formatting,
cargo test -p kon-storage, cargo test -p kon --lib commands::live::tests,
cargo check — all green.

Scope boundary: kon-llm crate is still a stub; task extraction remains
rule-based. Bundled local-LLM runtime is the next clean step and is not
in this commit.

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

src-tauri/src/commands/profiles.rs

@@ -11,6 +11,7 @@
 
 use serde::Serialize;
 
+use kon_ai_formatting::extract_corrections;
 use kon_storage::{
     add_profile_term as db_add_profile_term, create_profile as db_create_profile,
     delete_profile as db_delete_profile, delete_profile_term as db_delete_profile_term,
@@ -21,6 +22,8 @@ use kon_storage::{
 
 use crate::AppState;
 
+const AUTO_LEARNED_NOTE: &str = "Auto-learned from transcript edit";
+
 /// Frontend-facing profile shape. Matches the object the Svelte profile
 /// picker + editor will consume.
 #[derive(Debug, Clone, Serialize)]
@@ -145,6 +148,32 @@ pub async fn add_profile_term_cmd(
         .map_err(|e| e.to_string())
 }
 
+#[tauri::command]
+pub async fn learn_profile_terms_from_edit_cmd(
+    state: tauri::State<'_, AppState>,
+    profile_id: String,
+    original_text: String,
+    edited_text: String,
+) -> Result<Vec<ProfileTermDto>, String> {
+    let existing_terms: Vec<String> = db_list_profile_terms(&state.db, &profile_id)
+        .await
+        .map_err(|e| e.to_string())?
+        .into_iter()
+        .map(|row| row.term)
+        .collect();
+
+    let corrections = extract_corrections(&original_text, &edited_text, &existing_terms);
+    let mut learned = Vec::new();
+    for term in corrections {
+        let row = db_add_profile_term(&state.db, &profile_id, &term, AUTO_LEARNED_NOTE)
+            .await
+            .map_err(|e| e.to_string())?;
+        learned.push(ProfileTermDto::from(row));
+    }
+
+    Ok(learned)
+}
+
 #[tauri::command]
 pub async fn delete_profile_term_cmd(
     state: tauri::State<'_, AppState>,