Bind Git suppression checks to actual options #514

🤖 Generated by the Agentic Engineer

Problem and evidence

The read-only command guard counts Git execution-suppression words even when they are path operands. A private synthetic repository demonstrates that the admitted command can run its configured text converter; a genuine suppressed invocation does not.

Expected outcome

Required suppression must be established by actual options before the pathspec boundary. Filename operands cannot prove that Git will suppress external processing.

Acceptance criteria

• Reproduce the discrepancy using a real Git repository and a harmless converter fixture.
• Refuse suppression words supplied only as pathspecs.
• Cover relevant Git read commands and explicit option terminators.
• Preserve correctly suppressed ordinary read commands.
• Run guard and installed adapter tests without executing surveyed branch code.

Rough size: S. Part of #223.