feat: integrate nexus API commands as first-class noun-verb subcommands

[feluelle]

Description

Auto-generate CLI commands from the Astronomer API spec via the nexus shared library and register them directly on the root in noun-verb format (e.g. astro deployment create). Nexus commands take priority; remaining cloud commands fill gaps via automatic merge. This removes ~70 hand-written cloud commands now covered by the API spec.

Key changes

• ConfigAdapter: Bridges astro-cli's viper-based config to the nexus ConfigProvider interface, mapping domains to API profiles and contexts to org/workspace/deployment defaults
• Noun-verb registration: Nexus restish commands (e.g. create-deployment) are parsed and registered as astro <noun> <verb> (e.g. astro deployment create)
• Cloud command merge: Remaining cloud commands are merged underneath nexus nouns with nexus-first priority — cloud fills gaps for commands not covered by the API (e.g. astro deploy, astro deployment connection, astro deployment airflow-variable)
• Removed ~70 cloud commands: Deployment/workspace/organization CRUD, user/team/token management, inspect, hibernate, wake-up — all replaced by nexus-generated equivalents
• Interactive prompts: Missing required body fields are prompted interactively in terminals (enum fields show numbered selection; oneOf/discriminator fields prompt first)
• Delete confirmation: All delete commands prompt for confirmation; --force/-f skips the prompt
• Pretty-printed output: JSON output is pretty-printed with 2-space indentation in terminals; raw compact JSON when piped for scripting compatibility
• Error formatting: API errors displayed as Error (<status>): <message> instead of raw JSON
• Breaking changes doc: BREAKING_CHANGES.md documents all removed commands, removed features, and behavioral changes

🧪 Functional Testing

1. astro deployment list — should return pretty-printed JSON in terminal
2. astro deployment create — should prompt for required fields (type, name, etc.)
3. astro deployment delete <id> — should prompt for confirmation; --force skips it
4. astro deployment list | jq '.' — should return raw compact JSON when piped
5. astro deploy — should still work as before (project deployment)
6. astro workspace list / astro organization list — nexus-generated commands work
7. Verify commands not covered by nexus still work (e.g. astro deployment connection list)

📋 Checklist

• Rebased from the main (or release if patching) branch (before testing)
• Ran make test before taking out of draft
• Ran make lint before taking out of draft
• Added/updated applicable tests
• Tested against Astro-API (if necessary).
• Tested against Houston-API and Astronomer (if necessary).
• Communicated to/tagged owners of respective clients potentially impacted by these changes.
• Updated any related documentation

[coveralls-official]

Pull Request Test Coverage Report for Build 10fb78cd-b00c-4a9f-a1a6-a6ab27017b4d

Details

• 27 of 845 (3.2%) changed or added relevant lines in 7 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-2.3%) to 33.612%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
cmd/root_hooks.go	10	16	62.5%
cmd/root.go	16	40	40.0%
internal/nexus/output.go	0	32	0.0%
internal/nexus/config_adapter.go	0	81	0.0%
internal/nexus/commands.go	0	153	0.0%
internal/nexus/exec.go	0	522	0.0%

Files with Coverage Reduction	New Missed Lines	%
cmd/cloud/workspace.go	2	88.64%

Totals
Change from base Build f71991c9-5d72-45db-93b8-f9c82e50ab2c:	-2.3%
Covered Lines:	22310
Relevant Lines:	66375

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💛 - Coveralls