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/diagnostics.rs

@@ -60,9 +60,7 @@ pub fn install_panic_hook() {
              RUST_BACKTRACE: {bt}\n",
             ver = KON_VERSION,
             ts = ts,
-            thread = std::thread::current()
-                .name()
-                .unwrap_or("<unnamed>"),
+            thread = std::thread::current().name().unwrap_or("<unnamed>"),
             info = info,
             os = std::env::consts::OS,
             arch = std::env::consts::ARCH,
@@ -98,7 +96,11 @@ pub async fn log_frontend_error(
 
     log_error(
         &state.db,
-        if context.is_empty() { "frontend" } else { &context },
+        if context.is_empty() {
+            "frontend"
+        } else {
+            &context
+        },
         Some("FRONTEND_ERROR"),
         &message,
         metadata.as_deref(),
@@ -245,8 +247,10 @@ pub async fn generate_diagnostic_report(
         .unwrap_or(0);
     out.push_str(&format!("- Generated: unix `{}`\n", now));
     out.push_str("\n");
-    out.push_str("> This report is local-only until you choose to share it. \
-                  Review the contents below before sending to anyone.\n\n");
+    out.push_str(
+        "> This report is local-only until you choose to share it. \
+                  Review the contents below before sending to anyone.\n\n",
+    );
 
     if opts.include_settings {
         out.push_str("## Settings (sanitised)\n\n");
@@ -325,8 +329,10 @@ pub async fn generate_diagnostic_report(
     }
 
     out.push_str("---\n\n");
-    out.push_str("Generated by Kon. To share, copy the entire markdown above \
-                  and paste it into an email or issue. Email: jake@corbel.consulting.\n");
+    out.push_str(
+        "Generated by Kon. To share, copy the entire markdown above \
+                  and paste it into an email or issue. Email: jake@corbel.consulting.\n",
+    );
 
     Ok(out)
 }