fix: sanitize empty Read pages arguments

[icebear0828]

Summary

• Strip empty or whitespace-only pages from Claude Code Read tool calls during Codex -> Anthropic translation.
• Preserve non-empty PDF page ranges and all non-Read tool arguments.
• Add regression coverage for streamed and collected tool-call responses.

Verification

• npm test -- --run tests/unit/translation/codex-to-anthropic-read-pages.test.ts tests/unit/translation/codex-to-anthropic.test.ts
• npx vitest run tests/unit/translation/codex-to-anthropic.test.ts tests/unit/translation/tool-format.test.ts tests/unit/translation/anthropic-to-codex.test.ts
• npm run build
• npm test
• Device A real Claude Code worktree smoke: 3/3 successful with gpt-5.5-xhigh, no Read tool validation error

Fixes #558