[codex] fix Claude Code config import env parsing

[xuqian-git]

Summary

Fixes Claude Code config import when ~/.claude/settings.json contains Claude Code-specific env flags whose values are not strings.

Root Cause

The importer validated every key under settings.env as a string, even though Open CoDesign only consumes a small set of Anthropic import fields. A boolean flag such as CLAUDE_CODE_DISABLE_1M_CONTEXT caused the whole config to be classified as parse-error; the import IPC then surfaced that as a misleading "No Claude Code settings found" error.

Changes

• Validate only imported Anthropic env keys: ANTHROPIC_AUTH_TOKEN, ANTHROPIC_API_KEY, ANTHROPIC_BASE_URL, and ANTHROPIC_MODEL.
• Preserve validation for malformed imported fields.
• Surface direct import parse failures as CONFIG_PARSE_FAILED with the actual reason instead of reporting a missing file.
• Add regression coverage for non-string unrelated Claude Code env flags and the direct import parse-error branch.

Validation

• pnpm --filter @open-codesign/desktop exec vitest run src/main/imports/claude-code-config.test.ts src/main/onboarding-ipc.test.ts
• pnpm exec biome check apps/desktop/src/main/imports/claude-code-config.ts apps/desktop/src/main/imports/claude-code-config.test.ts apps/desktop/src/main/onboarding/register.ts apps/desktop/src/main/onboarding-ipc.test.ts
• pnpm --filter @open-codesign/desktop typecheck

Note: local pre-commit/pre-push hooks run full biome check . and were blocked by an unrelated untracked apps/desktop/release-local-arm64/ build directory in this checkout; that directory is not part of this PR.