[BUG] Issue CLI logical failure paths return exit code 0 (admin/vote/harvest)

[bitloi]

Description

Several issue CLI commands print error messages for logical failure branches but still exit with status code 0.
This causes scripts/CI to treat failed operations as success.

Affected command surfaces include:

• admin cancel-issue (issue not found, cancel result false)
• admin payout-issue (issue not found, payout result false)
• admin set-owner (result false)
• admin set-treasury (result false)
• admin add-vali (result false)
• admin remove-vali (result false)
• vote solution (result false)
• vote cancel (result false)
• harvest (failed/partial/None-style non-success outcomes)

Steps to Reproduce

1. Run one of the affected commands in a logical failure path (example: gitt admin cancel-issue <nonexistent_issue_id>).
2. Observe that an error is printed (for example: Issue <id> not found on contract.).
3. Check shell exit code (echo $?) and observe it is 0.

Expected Behavior

Logical command failures should exit non-zero (exit code != 0) so automation can detect failures reliably.

Actual Behavior

CLI prints failure/error output but returns exit code 0 for multiple logical-failure branches.

Environment

• OS: Linux (Ubuntu)
• Python version: 3.12.x
• Commit/Version: test branch (e.g. 4d47116 before fix)

Additional Context

This is inconsistent with existing exception failure handling in the same CLI, where _handle_command_error / handle_exception already exit non-zero.