feat: add centralized structured logging setup

[fmueller]

Summary

• add a new scribae.logging_config.setup_logging helper with idempotent handler setup, quiet-safe stream behavior, and optional file logging via SCRIBAE_LOG_FILE
• initialize logging in the root CLI callback and wire per-command verbosity into logging setup across brief/idea/write/meta/feedback/refine/translate commands
• add module-level debug logging in core generation/translation paths to improve traceability without changing normal command output
• keep --quiet behavior intact by preventing verbose debug stream logs when quiet mode is enabled

Validation

• uv run ruff check
• uv run mypy
• uv run pytest