feat: add alphabet filtering to strategy symbols

[pjy008008]

What changed

• Added an ALL and A–Z filter to the Basic strategy symbol picker.
• Disabled letters that have no available symbols and reset the filter when searching or reopening the picker.
• Kept the picker viewport compact and scrollable while rendering every symbol matching the active filter.
• Added Korean/English accessibility labels and interaction coverage.

Why

The supported catalog contains hundreds of symbols. Finding a ticker by scrolling alone was slow, and the previous 50-item render limit also hid valid matches from ALL and large alphabet groups.

User impact

Users can jump to a ticker's initial, scroll through the complete matching set without truncation, or type a search query as before.

Validation

• pnpm exec vitest run — 48 files, 580 tests passed
• pnpm typecheck
• pnpm build
• git diff --check