fix: run mode hangs forever on early-return commands like memory and trust

[LeXwDeX]

Why

opencode run "/memory" (and run --command memory) hangs forever with zero output, while the same command via serve POST /session/:id/command returns instantly.

Mechanism

Early-return command dispatches (/memory at packages/opencode/src/session/prompt.ts:1887-1927, same shape as /trust) write a user message + text parts and return WITHOUT any assistant step. The run CLI waits for a turn-completion signal (assistant step-finish / session idle) that these commands never emit, so it waits forever.

Evidence

• Local main build (post-fix: headless init does not stamp project time_initialized so memory stays inert #405): run "/memory" hangs in bare and configured repos alike; serve + /command {command:"memory"} returns the full parts payload in <1s
• v1.0.29 binary: run --command memory hangs identically - pre-existing gap, NOT a fix: headless init does not stamp project time_initialized so memory stays inert #405 regression (before fix: headless init does not stamp project time_initialized so memory stays inert #405 the text path never reached the real dispatch; the model improvised an answer)
• fix: headless init does not stamp project time_initialized so memory stays inert #405 made the text path route to the real dispatch, so the gap is now reachable via run "/memory"

Acceptance

• opencode run "/memory" prints the status and exits
• run "/trust", run "/goal" (same early-return shape) verified
• Regression test: run-mode early-return command completes (exit 0, output non-empty)

[LeXwDeX]

Delivered via PR #411 (merged to dev): run-mode turns complete for early-return commands. specgit finish exit 0.