fix(cli): print help for init/update/uninstall instead of running them

[latekvo]

The bug

argent <cmd> --help for the installer subcommands init / install / update / uninstall / remove did not print help — it ran the real, side-effecting command. argent uninstall --help even opened the destructive "Remove argent configuration from this workspace?" prompt (with Yes pre-selected).

Root cause: main() in packages/argent/src/cli.ts dispatched these subcommands and forwarded rest (including --help) to the installer functions, which have no help handling. Only the top-level --help case called printHelp().

The fix

Intercept --help/-h for exactly the installer command set before dispatching, and print a short per-subcommand usage block without loading or invoking any installer code (no network, no wizard, no prompt).

• New side-effect-free module packages/argent/src/installer-help.ts exports the pure decision function installerHelpRequested(command, rest) plus printInstallerHelp(command).
• cli.ts calls the guard at the top of main() and returns early when help is requested.
• The other subcommands (run, tools, server, link, flags, enable, disable, telemetry) already handle --help themselves, so they are deliberately excluded — argent run <tool> --help still prints that tool's flags.

Verification

• npm run build (root tsc) + npm run build -w @swmansion/argent — green.
• Ran the built CLI end-to-end (stdin from /dev/null): init --help, update --help, uninstall --help, install --help, remove --help, uninstall -h all print usage and exit 0 with no wizard/network/prompt.
• Regression: argent --help still prints top-level help; argent run --help still prints the run usage (not intercepted).
• Added unit tests in packages/argent/test/installer-help.test.ts for installerHelpRequested / isInstallerCommand (8 tests, all pass).
• prettier and eslint clean on the touched files; test typecheck passes.

Fixes #451

[hubgan]

Reviewed the installer-help short-circuit and exercised it end-to-end against the built CLI: the five installer subcommands now print usage and exit 0 without running, argent uninstall --help and remove --help leave an existing workspace's config byte-for-byte unchanged (no prompt, nothing deleted), and run / tools / server still handle their own --help unaffected. I also confirmed the pre-fix behaviour — uninstall derives non-interactivity only from --yes, so --help previously fell through to the destructive confirm. The fix is correct; the inline notes are mostly about test coverage of the dispatch path.

[hubgan]

Reviewed and verified this end-to-end: built the CLI and ran every installer --help form against the real dispatcher. Each prints usage and exits 0 without loading the installer bundle, and uninstall --help in a workspace populated with argent config leaves every file untouched. The option lists in INSTALLER_COMMAND_META match the real init/update/uninstall parsers, and non-installer commands (run/tools) still handle their own --help. A few low-severity notes inline.