refactor(frontend): migrate JS modules to TypeScript

Wholesale JS -> TS migration of the frontend — stores, utils, actions,
and all Svelte component scripts adopt type annotations. Compile-time
surfaces (app.d.ts, lib/types/) added for shared DTO types.

Build plumbing:
  - package.json: dev:frontend script that runs svelte-kit sync first
  - tauri.conf.json: beforeDevCommand points at dev:frontend
  - run.sh: dropped the sed-hack that temporarily blanked beforeDevCommand;
    now relies on npm run dev:frontend to avoid double-Vite
  - jsconfig.json: allowImportingTsExtensions

Preserves all Group 1 behaviour:
  - page.svelte.ts keeps loadHistory / loadTasks Tauri-first, no
    localStorage; saveTranscriptMeta + mapTranscriptRow + mapTaskRow
    intact; update_task_cmd and update_transcript_meta_cmd invocations
    carry the correct payload shape.
  - Toasts, preferences stores typed without behaviour change.
  - Viewer still routes segment edits through saveTranscriptMeta; the
    Task 1.5 TODO markers are gone.

taskExtractor.ts is functionally improved during the migration:
  - multi-task matches in the same sentence
  - list-style shopping-verb expansion (get bread, milk, and cheese)

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

run.sh

@@ -8,19 +8,15 @@ cd "$(dirname "$0")"
 export LIBCLANG_PATH=/usr/lib64/llvm21/lib64
 
 printf 'Starting Vite dev server...\n' >&2
-npm run dev &
+npm run dev:frontend &
 VITE_PID=$!
 
 until curl -sf http://localhost:1420 > /dev/null 2>&1; do sleep 0.5; done
 printf 'Vite ready. Launching Tauri...\n' >&2
 
-# Blank beforeDevCommand so Tauri doesn't spawn a second Vite
-sed -i 's/"beforeDevCommand": "npm run dev"/"beforeDevCommand": ""/' src-tauri/tauri.conf.json
-
 cleanup() {
-    sed -i 's/"beforeDevCommand": ""/"beforeDevCommand": "npm run dev"/' src-tauri/tauri.conf.json
     kill "$VITE_PID" 2>/dev/null || true
 }
 trap cleanup EXIT INT TERM
 
-npx tauri dev
+npx tauri dev --config '{"build":{"beforeDevCommand":""}}'