fix(server): CJK-aware charWidth — fixes box alignment on zh/ja/ko terminals

[nanami-he]

What broke

On a Chinese-locale Windows 11 box (system code page 936), /pet browse returns visibly broken boxes:

╭────────────────────────────────────╮
│ 1. Owl                             │
├────────────────────────────────────┤
│      {◉,◉}                         │   ← right │ drifts past ╮
│      /)_)                          │
│    ——" "——                         │   ← same here
├────────────────────────────────────┤
│ Quiet, curious — the scholar who … │
╰────────────────────────────────────╯

The art uses several Unicode "Ambiguous East Asian Width" characters — ◉ (U+25C9), — (U+2014), ✦/✧, ★, Λ, ×. Per UAX #11 these render as 2 columns on East Asian locale terminals (Chinese/Japanese/Korean Windows Terminal, iTerm2 under zh/ja/ko, …) and 1 column elsewhere. charWidth() was always returning 1, so stringWidth() under-counted and pad() left the right border too far out.

Fix

server/utils.ts now detects the locale and treats the relevant Ambiguous-width ranges as 2 cols when CJK:

• POSIX env vars (LC_ALL / LC_CTYPE / LANG / LANGUAGE) — Mac/Linux happy path
• Intl.DateTimeFormat().resolvedOptions().locale — Windows fallback (env vars are usually unset there but the system locale is e.g. zh-CN)

When CJK is detected, these ranges become 2-wide:

Range	Block	Examples used in art
0x2010–0x2027, 0x2030–0x205E	General Punctuation	—
0x2150–0x218F	Number Forms	—
0x2190–0x21FF	Arrows	—
0x2200–0x22FF	Mathematical Operators	Λ (technically Greek but kept narrow)
0x2580–0x25FF	Block Elements + Geometric Shapes	◉
0x2600–0x26FF	Misc Symbols	—
0x2700–0x27BF	Dingbats	✦, ✧

Box-drawing (0x2500–0x257F) is intentionally excluded — every mainstream terminal special-cases box drawings to 1-wide for TUI sanity even under a CJK locale. Including them here would double the border width.

charWidth / stringWidth / padDisplay all gained an optional explicit cjk parameter (defaulting to the auto-detected locale) so tests are deterministic regardless of where the suite happens to run.

Test plan

• bun test — 305 → 307 pass (added explicit non-CJK + CJK + box-drawing cases)
• Smoke test on Win11 (zh-CN, code page 936): charWidth('◉') === 2, charWidth('─') === 1, IS_CJK_LOCALE === true. animalCard() for Owl now produces a card whose right border lines up with the top.
• Sanity check on macOS — confirm non-CJK locale still returns 1 for ◉/— and existing 12-wide art lines stay 12-wide.
• After merge: npx petsonality@<next> /pet browse on a fresh CJK Windows box.

Out of scope (separate PR)

bun run build on Win11 still fails at build:art until #7 lands — that's an independent path-resolution bug, not coupled to this fix.

🤖 Generated with Claude Code

[nanami-he]

shipped in v0.4.4. CJK alignment now correct on zh/ja/ko terminals.