fix(commit): created commits before agent teardown

- Ran commit host completion before commit-agent session disposal so mnemopi/autolearn teardown cannot preempt a valid proposal.

- Converted missing commit-agent host outputs and split-plan gaps into thrown errors so omp commit cannot resolve into exit 0 without creating a commit.

- Preserved caller GPG_TTY state instead of forcing a bogus signing TTY in git and non-interactive subprocess environments.

Fixes #4794

packages/coding-agent/src/exec/non-interactive-env.ts

@@ -15,7 +15,6 @@ export const NON_INTERACTIVE_ENV: Readonly<Record<string, string>> = {
 	LESS: "FRX",
 	// Disable terminal features that can block the process.
 	TERM: "dumb",
-	GPG_TTY: "not a tty",
 	NO_COLOR: "1",
 	PYTHONUNBUFFERED: "1",
 	// Disable editor and terminal credential prompts.