hcom 0.7.4

Patch release focused on event subscription reliability, terminal launch error reporting, and config initialization.

• Event subscription hardening — SQL expressions in events sub --sql are now validated before the subscription is created, returning a clear error on invalid SQL rather than silently misbehaving. Subscription IDs are now deterministic (SHA256 of caller + filters + once-mode), so re-registering the same subscription is idempotent instead of creating duplicates.

• macOS terminal file-open semantics — Fixed open -a <App> rewriting: app path substitution is now skipped for commands that don't pass --args, preserving the open -a Terminal {script} form that macOS requires for file-open launches. Commands that do use --args still get the absolute bundle path substituted as before.

• AI tool terminal launch hints — When a terminal launch fails from inside a managed AI tool session, the error now includes an actionable hint. tmux failures get specific remediation steps.

• Lazy config initialization — Config::get() now initializes from the environment on first access instead of requiring an explicit Config::init() call beforehand, eliminating a class of panics in contexts where init was missed.

• Launch failure reporting — Improved launch status tracking across PTY, DB, and instance lifecycle to surface failures more clearly.

• Test fixes — PTY delivery test logs now write to target/test-logs/ within the project, output goes to stdout for visibility with --nocapture, and the macOS-only command extension test is gated with #[cfg(target_os = "macos")].