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/audio.rs

@@ -67,18 +67,17 @@ pub async fn start_native_capture(
     // worst case). Run on a blocking thread so the async runtime stays
     // responsive to other Tauri commands. (Codex review 2026/04/17 D2)
     let device_name_for_blocking = device_name.clone();
-    let (capture, rx) = tokio::task::spawn_blocking(move || {
-        match device_name_for_blocking.as_deref() {
+    let (capture, rx) =
+        tokio::task::spawn_blocking(move || match device_name_for_blocking.as_deref() {
             Some(name) if !name.is_empty() => MicrophoneCapture::start_with_device(name),
             _ => MicrophoneCapture::start(),
-        }
-    })
-    .await
-    .map_err(|e| format!("audio task join error: {e}"))?
-    .map_err(|e| {
-        eprintln!("[native-capture] MicrophoneCapture::start failed: {e}");
-        e.to_string()
-    })?;
+        })
+        .await
+        .map_err(|e| format!("audio task join error: {e}"))?
+        .map_err(|e| {
+            eprintln!("[native-capture] MicrophoneCapture::start failed: {e}");
+            e.to_string()
+        })?;
     eprintln!(
         "[native-capture] cpal capture started successfully on '{}'",
         capture.device_name
@@ -150,7 +149,9 @@ pub async fn start_native_capture(
                     }
                     Err(std::sync::mpsc::TryRecvError::Empty) => break,
                     Err(std::sync::mpsc::TryRecvError::Disconnected) => {
-                        eprintln!("[native-capture] capture stream disconnected; accumulator exiting");
+                        eprintln!(
+                            "[native-capture] capture stream disconnected; accumulator exiting"
+                        );
                         capture_dead = true;
                         break;
                     }
@@ -166,9 +167,12 @@ pub async fn start_native_capture(
                     all.extend_from_slice(&chunk);
                 }
 
-                let _ = app.emit("native-pcm", serde_json::json!({
-                    "samples": chunk,
-                }));
+                let _ = app.emit(
+                    "native-pcm",
+                    serde_json::json!({
+                        "samples": chunk,
+                    }),
+                );
             }
 
             if capture_dead {
@@ -185,9 +189,12 @@ pub async fn start_native_capture(
             if let Ok(mut all) = all_samples_clone.lock() {
                 all.extend_from_slice(&pcm_buffer);
             }
-            let _ = app.emit("native-pcm", serde_json::json!({
-                "samples": pcm_buffer,
-            }));
+            let _ = app.emit(
+                "native-pcm",
+                serde_json::json!({
+                    "samples": pcm_buffer,
+                }),
+            );
         }
 
         // Drop the capture to stop the cpal stream