fix: /init stamp is lost to an event-listener race, leaving MEMORY fail-closed with no self-heal

[LeXwDeX]

Why

MEMORY activation is gated on project.time_initialized, which is stamped only by an event listener: Project.initState subscribes to Command.Event.Executed and calls setInitialized when it sees the init command (packages/opencode/src/project/project.ts:418-424). If the event is missed - subscription not yet established when /init runs, or the command executed through a path that does not reach that instance's event stream - the stamp is never written. The user then gets "Memory is unavailable until the project is initialized - run /init first, then /memory on" and re-running /init can lose the same race again. Real case: a project (git identity from remote URL) whose earlier clone directory was deleted carried time_initialized = NULL forever; the only recovery was manual sqlite surgery or a lucky re-run.

Scope

• Self-heal: when the activation gate finds time_initialized NULL but the project worktree already has a non-empty AGENTS.md (the artifact /init produces), stamp it automatically instead of reporting the blocker.
• Diagnostics: when the gate still blocks, /memory status (statusReason) includes the actual DB row state (stamp NULL vs set, worktree path, sandboxes list) so stale-identity cases are visible at a glance.
• Regression tests: NULL stamp + AGENTS.md present -> activation succeeds; NULL stamp + no AGENTS.md -> blocker message still reported with diagnostics.

Acceptance

• A project with AGENTS.md present can enable MEMORY without re-running /init (race becomes harmless).
• A project never initialized still reports the run-/init-first blocker, now with DB diagnostics.
• Existing memory gate tests keep passing; specgit finish exits 0.