[Epic] Make the CLI drivable without reading its source (agent/CI ergonomics)

[Bccorb]

Tracking issue for the findings from an unassisted run of seamless init by an agent with no
prior knowledge of the CLI. The verdict was that the tool is drivable only because the source
was available to read: the prompt sequence, the option ordering, and the alias names all had
to come from src/prompts/projectSetup.ts and registry.json. Without that checkout it is a
hard CLI to drive.

What worked, and should not regress

• Errors from whoami and apps list name the exact command to run next, which is what let
  a logged-out state get detected up front instead of halfway through a prompt sequence.
• Every (recommended) option is also the initialValue or the first option, so a blind
  Enter produces the right answer.
• discard() plus the SIGINT handler means a half-built scaffold does not block a retry.
• The success output gives exact URLs, exact next steps, and calls out the
  OWNER_EMAIL-must-change-before-registering caveat explicitly.

The list

• Parse -h / --help in every command ahead of its own argument parsing. Shipped in feat: add per-command help #148.
• feat: add seamless templates list --json for template discovery #150 seamless templates list [--json], so ids, aliases, and kinds are discoverable
  without a source checkout. Shipped in feat: make init template flags discoverable and validated up front #155.
• feat: accept template ids as init flags (--react-vite alongside --basic) #151 Accept template ids as init flags (--react-vite alongside --basic), and give
  the api templates a flag at all. Shipped in feat: make init template flags discoverable and validated up front #155.
• fix: validate init template flags before the non-empty-directory prompt #149 Validate init template flags before the non-empty-directory prompt, so no
  unrecognized flag routes through an overwrite confirmation on its way to an error.
  Shipped in feat: make init template flags discoverable and validated up front #155.
• feat: non-interactive seamless init --yes with full flag coverage #152 Non-interactive seamless init --yes with full flag coverage. Shipped in feat: add a non-interactive seamless init #156.
• feat: fail fast when init runs without an interactive terminal #153 Fail fast when init runs without an interactive terminal. Shipped in feat: fail fast when init has no terminal to prompt on #158
  (feat: fail fast when init has no terminal to prompt on #157 merged into its stacked base rather than main, so it was re-landed).
• feat: extend the no-terminal guard to every command that prompts #159 Extend the same guard to every other command that prompts, with --force (aliases
  --yes, -y) answering the destructive confirmations. Shipped in feat: extend the no-terminal guard to every command that prompts #160.

All of it is on main and queued for release in #121 (0.11.0).

What the CLI looks like now

The scenario that opened this issue, driven with no source checkout:

seamless templates list                 # discover the starters and their flags
seamless init my-app --local --yes \
  --email=you@example.com --react-vite --express

Runs unattended, with no pty. Every question has a flag, unspecified values take the
recommended option, and the destructive steps (writing over a non-empty directory, rotating a
service token) still require --force rather than being swept up by --yes. Nothing renders a
prompt to a pipe: every command stops naming the flag that answers the question.

Known limits

• The one-time code at login has no flag form, since it does not exist until the code is
  sent. login is not fully scriptable, which is inherent to OTP.
• --admin=source ([P1] adminMode: "source" scaffolds a broken stack — admin/ is never created #82) and --auth=local ([P2] "Enable Docker?" confirm is ignored; non-docker success output is unreachable #92) now have flags, but the underlying behavior
  is still broken. The flags will follow whatever those issues settle on.

[Bccorb]

Work is up as three stacked PRs:

• feat: make init template flags discoverable and validated up front #155 -> main: template flags discoverable and validated up front (fix: validate init template flags before the non-empty-directory prompt #149, feat: add seamless templates list --json for template discovery #150, feat: accept template ids as init flags (--react-vite alongside --basic) #151)
• feat: add a non-interactive seamless init #156 -> feat: make init template flags discoverable and validated up front #155: non-interactive init --yes (feat: non-interactive seamless init --yes with full flag coverage #152)
• feat: fail fast when init has no terminal to prompt on #157 -> feat: add a non-interactive seamless init #156: fail fast without a terminal (feat: fail fast when init runs without an interactive terminal #153)

Merge in that order. #153 stays open after #157 for the commands outside init that still hang on a prompt (login, profile, config apply, users delete, sessions revoke).

[Bccorb]

Status correction: #155 and #156 are on main. #157 merged into its stacked base after that base had already merged, so the terminal guard never reached main. Re-landed as #158 (a clean cherry-pick of the same commit onto main).

[Bccorb]

All seven items shipped and merged to main. Release queued in #121 as 0.11.0.