📝 Write an ADR for noun-first CLI restructure

Note — do not pre-claim an ADR number. This issue deliberately does not name one.
Pick the number when the file is actually written, by checking the highest number both
on main and in open PRs (PR #393 currently holds 126-132 for the multi-region set;
main is at 134 as of this note). This issue previously said ADR-122, then ADR-133 — both
were taken out from under it, because numbers get claimed in titles and branches long
before the file exists while main only knows the numbers already merged.

Description

Write an ADR documenting the decision to restructure the CLI from its current organic layout to a noun-first command hierarchy.

Current State

The CLI has grown organically with a mix of patterns:

Proposed Structure (ADR Content)

The ADR must document the following decisions:

1. Top-level nouns: stack, system, resource, entity, audit, usage, local, load

2. Consistent verb set: get, list, set, delete, create, deploy (max 2 levels of nesting: noun verb)

3. Global options: --name, --region, --endpoint-url are defined on the root group and inherited by all subcommands

4. Mapping table (current -> new):

5. Entity config sub-operations decision: Whether entity set covers both entity creation and limit configuration, or limits need a sub-noun (entity config set vs entity set --resource). The ADR must decide between:

• entity set --resource gpt-4 -l rpm:1000 (flat with --resource flag)
• entity config set --resource gpt-4 -l rpm:1000 (3-level nesting, violates max-2 rule)
• Keep entity set-limits as a hyphenated verb (exception to the verb set)

6. Legacy alias strategy:

• Old commands remain as hidden aliases for 2 minor versions
• Aliases emit deprecation warnings to stderr
• Removed in the next major version (v2.0.0)

7. Cross-noun query resolution:

• entity list-resources becomes resource list --with-entity-configs
• Queries belong under the noun that represents the result type

Acceptance Criteria

• docs/adr/<N>-noun-first-cli.md exists with Status: Proposed, where <N> is chosen at write time per the note above (highest number on main and in open PRs, +1)
• ADR follows the format from ADR-000 (max 100 lines, required sections: Context, Decision, Consequences, Alternatives Considered)
• Decision section contains: (a) the noun list, (b) the verb set, (c) global options list, (d) the entity config sub-operation decision, (e) legacy alias deprecation timeline, (f) cross-noun query rule
• Alternatives Considered section addresses at least: verb-first hierarchy, flat (no grouping), and 3-level nesting
• No code examples or implementation checklists in the ADR (per ADR-000)

Start by reading docs/adr/ADR-000 and checking the highest ADR number on main and in open PR #393 before choosing the filename. Write a Proposed ADR under docs/adr/ with the required sections, noun-first decisions, alternatives, alias timeline, and cross-noun query rule, staying under 100 lines and omitting code examples and implementation checklists.