fix: provider output handling and watch rebuild re-invocation

Provider info and error messages containing newlines broke the TTY
progress display (timer drifting to a new line, broken cursor
movement). Extract only the first line for progress events via
firstLine(). Full messages remain available through the provider's
own debug message type.

Skip provider services during watch rebuild convergence by adding a
SkipProviders flag to CreateOptions, set only by the watch rebuild
path. This prevents unnecessary re-invocation of providers on every
file change while preserving normal provider execution for all other
commands (up, create, run, scale).

Signed-off-by: Guillaume Lours <glours@users.noreply.github.com>