CLI error handling and exit status consistency.

## Summary

`printcraft-cli text --page N` returns exit status 0 after reporting that the selected page cannot be read. This occurs for a nonexistent page and for an explicitly selected page in a password-protected document opened without its password. Scripts that check the exit status cannot distinguish these failures from successful extraction.

## Runtime or environment

Runtime reproduction used the official macOS universal CLI release v0.2.1, tag commit `dcb00238896e418b357e6dd777ee35bad36f0b97`, on macOS 27.0, Darwin 27.0.0, Apple silicon. The release zip matched its published SHA256SUMS.txt; the extracted binary SHA-256 was `b7783b596870ed5a326f29456d4647382d2e1e4d7b7ffe75ded192cd15b86995`.

The current default branch was inspected at `1c78ff479ce5cf5cbcf7af5100378c9311b95162`. Its CLI text implementation, rendering implementation, and vendored parser source are unchanged relative to the release. The branch was not built or executed; the runtime observations below are from the release binary.

## Steps to reproduce

1. Put the verified release binary on PATH as `printcraft-cli` and work in an empty disposable directory.
2. Create a synthetic three-page PDF using Python 3. This fixture contains only fake text and no personal metadata.

```python
from pathlib import Path
objects = [b'>',
b'>',
b'>']
for page in ra...