feat(run:packaged): cohesive build+package+run against an ephemeral profile
Adds an `isEphemeralProfile()` helper (`dev`, `test-*`, `tmp-*`) and
uses it ONLY for the single-instance-lock skip in
`requestSingleInstance`. `isTestProfile()` continues to gate the
Playwright-specific behaviors (dock hide, session restore skip, etc.)
so `tmp-*` profiles get production-like UX: dock visible, close-on-
blur active, session restore, default-browser prompt, etc.
Replaces the existing `run:packaged` (which used `open` and couldn't
pass env vars, couldn't rebuild, and collided with any running prod
instance) with a single command that: kills any prior packaged
instance, runs `yarn build`, packages via `electron-builder --dir`,
then launches `out/mac-arm64/Peek.app/Contents/MacOS/Peek` in the
terminal foreground with `PROFILE=tmp-<timestamp>`.
The other `run:packaged:*` variants (`:debug`, `:bg`, `:debug:bg`,
`:check`) are unchanged — they still hit the binary directly for
post-hoc runs without a rebuild.
Reverts the earlier band-aid that gated `applyDockPreference` on
`E2E_TEST` instead of `isTestProfile()` — with the `tmp-*` path in
place that workaround is no longer needed.