Clean up stale dev-command and framework references in CLAUDE.md #73

Surfaced during the supply-chain hardening audit in #68 (and partially fixed there — the next.config.ts → next.config.mjs drift was corrected, but other drift remains).

Location: CLAUDE.md:5-11 (the "Development Commands" section)

Issue: Two stale references that mislead anyone (human or LLM) reading the doc:

• bun build is listed but the actual script (per package.json) is bun run build. bun build is the standalone Bun bundler, not Next.js — running it would do the wrong thing.
• bun lint - Run ESLint says ESLint, but the project actually uses Biome (bun run lint → biome lint).

Proposed fix: rewrite the section to match the actual scripts and tooling. Either align with package.json's script names exactly (use bun run <name> consistently) or move this section to reference README.md, which already has the correct version.

Priority: doc hygiene, not security. Pick up in any natural doc-touch PR rather than as a standalone change.