chore: complete cli beta acceptance

build: define cli distribution artifacts

ci: add cli packaging and integration gates

test: validate cli installation on clean machines

test: add real cli integration coverage

docs: rewrite onboarding around cli usage

docs: add cli help and shell completion support

build: add one-command cli installers

build: package cli for standard installation flows

fix: stabilize cli errors and exit codes

feat: polish cli progress and terminal output

feat: add cli image workflow commands

feat: add cli audio workflow commands

feat: add cli subtitle commands

feat: add cli concat command