Promote aitools skills-management commands to top-level

[jamesbroadhead]

Summary

• Promotes the aitools skills-management surface to top-level databricks aitools: install, update, uninstall, list, version
• Source files for the promoted surface (and the agents/installer libs they depend on) physically move from experimental/aitools/ to a new top-level aitools/ package, so directory layout matches stability tier
• Keeps the tools subtree under experimental/aitools/ — query, discover-schema, get-default-warehouse, statement — because tools.go still says "There are no stability guarantees for these tools"
• The hidden skills alias group also stays under experimental/aitools/
• The old paths under databricks experimental aitools install/update/uninstall/list/version and databricks experimental aitools skills install/list keep working as silent backward-compat aliases — no deprecation warning fires, the commands just forward

The aitools skills-management surface is feature-complete after the 5-PR series (#4810–#4814) that added state tracking, lifecycle commands, and project scope support. The tools subtree is functionally useful but its shape is still in flux, so promoting only the stable half.

Command shape after this PR

# Stable, top-level
databricks aitools install      # use --skills <name>[,<name>...] for specific skills
databricks aitools update
databricks aitools uninstall
databricks aitools list
databricks aitools version

# Silent backward-compat aliases (no warning)
databricks experimental aitools install/update/uninstall/list/version
databricks experimental aitools skills {list,install}

# Experimental, unchanged path
databricks experimental aitools tools query
databricks experimental aitools tools discover-schema
databricks experimental aitools tools get-default-warehouse
databricks experimental aitools tools statement {submit,get,status,cancel}

Test plan

• databricks aitools --help shows install/update/uninstall/list/version (no tools)
• databricks --help lists aitools in the output
• databricks experimental aitools install runs without warning and the work happens (silent alias)
• databricks experimental aitools tools query … runs as before
• databricks experimental aitools tools --help lists query/discover-schema/get-default-warehouse/statement
• Existing aitools tests pass plus new alias-forwarding coverage in experimental/aitools/cmd/skills_test.go

This pull request was AI-assisted by Isaac.

[github-actions]

Approval status: pending

/cmd/apps/ - needs approval

Files: cmd/apps/init.go
Suggested: @arsenyinfo
Also eligible: @MarioCadenas, @pkosiec, @fjakobs, @keugenek, @calvarjorge, @Shridhad, @atilafassina, @igrekun, @pffigueiredo, @ditadi

/experimental/aitools/ - needs approval

4 files changed
Suggested: @arsenyinfo
Also eligible: @MarioCadenas, @pkosiec, @fjakobs, @lennartkats-db, @keugenek, @calvarjorge, @Shridhad, @atilafassina, @igrekun, @pffigueiredo, @ditadi

General files (require maintainer)

36 files changed
Based on git history:

• @simonfaltum -- recent work in experimental/aitools/cmd/, ./, .github/

_{Any maintainer (@andrewnester, @anton-107, @denik, @pietern, @shreyas-goenka, @simonfaltum, @renaudhartert-db) can approve all areas.
See OWNERS for ownership rules.}

[simonfaltum]

I think we should move the code itself (the files) out of experimental as part of this as well.

[arsenyinfo]

No findings.

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🔍 Reviewed by nitpicker

[jamesbroadhead]

Hi @lennartkats-db — Claude here, on James's behalf.

This PR has changed shape since you were originally tagged. A heads-up before you take a look:

Simon is now effectively a co-author. He force-pushed and rewrote the branch on Apr 30 — the original commits are gone. The current commits implement the "promote skills surface, keep tools experimental" approach: source files for install/update/uninstall/list/version physically moved to a new aitools/ package, while tools and the skills alias group stay in experimental/aitools/. Old paths under experimental aitools keep working as silent backward-compat aliases (no deprecation warning).

Branch is now rebased onto current main and includes a couple of follow-up fixes from a self-review pass:

• experimental aitools Long help text was stale (advertised hidden subcommands) — now a one-liner pointing at the canonical path
• databricks aitools install <skill-name> now accepts a positional to match the legacy alias's behavior; positional and --skills are mutually exclusive

CI: all standard checks green. Integration Tests show one failure (https://go/deco-tests/25155597272) — the changes here shouldn't be touching anything integration-relevant, so it reads as a flake, but worth a quick triage if you happen to be looking.