A launcher provides three values before the tree mounts: ctx.cmdlineArgs
(get() is the whole interface) carrying everything after its own flags,
ctx.appExit for a bounded exit, and ctx.appPatches for decisions a later
recomposition must keep. An app's startup row injects cmdlineArgs and calls
runStartup() with its own commander program.
Rows the app configures inject its startup service, so they wait until the
startup row has resolved their values and provided it; --help prints,
disables those rows, and exits without the app ever starting.
A changed row is recycled — disabled, then re-enabled with its new values —
because a row's config is resolved when the Loader creates its fiber, while
the row is still waiting. Recycling never touches inject: an inject update
restarts the row from its unwrapped callback and loses the plugin's own
static injections. A mount still in flight is allowed to settle first, so
the disable has a fiber to dispose instead of racing one into existence.
