This pull request fixes several runtime and reporting issues found by the examples auto-run:

• reports Runloop cleanup failures without masking successful example execution
• avoids claiming Modal bucket I/O when no bucket is mounted
• accurately reports missing Runloop policies instead of describing them as retained
• awaits the Codex tool input filter
• allows trusted host virtual environments to support nested sandbox Python execution while preventing manifest environment overrides from broadening host filesystem access
• updates sandbox memory examples and adds regressions for the affected behavior

The virtual-environment grant remains read-only and does not expose the parent project directory.