phase 3: stronger deprecation notice for run/architect/scaffold/login in charter CLI

[stackbilt-admin]

Phase 3 of RFC #112 — surface a stronger runtime deprecation notice in @stackbilt/cli pointing users at @stackbilt/build after it's published.

Context

• Phase 1 (env-var bridge + charter login deprecation notice): shipped in feat(cli): STACKBILT_API_KEY env var auth; deprecate charter login #111.
• Phase 2 (stand up @stackbilt/build): prerequisite — notice can't link to a real package until @stackbilt/build is on npm.
• README-level deprecation: already landed in docs: lead README with governance; remove build-hero + images #124 (Build section of root README flagged, pointing at RFC RFC: Extract commercial surface from @stackbilt/cli into @stackbilt/build #112).

Scope

On every invocation of charter run, charter architect, charter scaffold, charter login:

1. Print a warning notice to stderr indicating the command is deprecated and will be removed in Charter 1.0.
2. Link to @stackbilt/build as the replacement (npm install -g @stackbilt/build).
3. Notice is pre-execution; command still runs after (no behavior change yet).

Suggested format:

⚠ charter run is deprecated and will be removed in Charter 1.0.
  Install @stackbilt/build for the long-term home of this command:
    npm install -g @stackbilt/build
  See https://github.com/Stackbilt-dev/charter/issues/112 for context.

Acceptance criteria

• All four deprecated commands print the notice once per invocation before executing.
• Notice writes to stderr (doesn't pollute stdout for --format json consumers).
• Notice suppressible via --no-deprecation-warning flag or CHARTER_NO_DEPRECATION_WARNING=1 env var.
• Tests assert the notice is emitted for each deprecated command.
• Ships in a minor version bump.

Blocked on

• Phase 2 (@stackbilt/build must be publishable before the notice can link to a real package).

References

• RFC RFC: Extract commercial surface from @stackbilt/cli into @stackbilt/build #112 (parent umbrella)
• Phase 1: feat(cli): STACKBILT_API_KEY env var auth; deprecate charter login #111 (env-var bridge, existing charter login deprecation)
• Phase 2: stand up @stackbilt/build
• Phase 4: full removal at Charter 1.0