Move U2M authentication implementation into the CLI

[renaudhartert-db]

Changes

Moves interactive U2M authentication and token caching into a CLI-owned libs/auth/u2m package and updates all CLI callers to use it. The implementation preserves the SDK behavior while routing browser launches through the CLI browser abstraction.

Note: This PR purely aims at collocating the code by moving the CLI relevant parts back to the CLI repo. This PR will be followed by subsequent PRs to simplify the implementation now that all code is collocated.

Why

Interactive login and persistent token storage are CLI responsibilities, but the CLI depended on SDK types such as PersistentAuth that the SDK itself does not use for authentication. Owning these pieces in the CLI removes that cross-layer dependency.

Tests

• ./task lint: Go lint passes with zero issues; Python lint could not download Ruff because DNS is unavailable
• ./task test: all 9,650 unit tests pass; acceptance prerequisites fail because the installed jq is 1.6 and the suite requires 1.7
• SDK companion validation: formatting, lint, and all 1,467 tests pass

Written with Codex.

[github-actions]

Approval status: pending

/cmd/auth/ - needs approval

4 files changed
Suggested: @simonfaltum
Also eligible: @tanmay-db, @mihaimitrea-db, @tejaskochar-db, @Divyansh-db, @hectorcast-db, @parthban-db, @chrisst, @rauchy

/libs/auth/ - needs approval

38 files changed
Suggested: @simonfaltum
Also eligible: @tanmay-db, @mihaimitrea-db, @tejaskochar-db, @Divyansh-db, @hectorcast-db, @parthban-db, @chrisst, @rauchy

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

[eng-dev-ecosystem-bot]

Integration test report

Commit: f8b3b93

Run: 34041991029

	Env	💚​RECOVERED	✅​pass	🙈​skip	Time
💚​	aws linux	1	275	15	5:15
💚​	aws windows	1	277	13	4:14
💚​	azure linux	1	274	15	5:07
💚​	azure windows	1	276	13	4:55
💚​	gcp linux	1	275	15	5:23
💚​	gcp windows	1	277	13	4:58

	Test Name	aws linux	aws windows	azure linux	azure windows	gcp linux	gcp windows
💚​	TestAccept	💚​R	💚​R	💚​R	💚​R	💚​R	💚​R

Top 6 slowest tests (at least 2 minutes):

duration	env	testname
4:55	gcp windows	TestAccept
4:52	azure windows	TestAccept
4:11	aws windows	TestAccept
3:56	aws linux	TestAccept
3:52	azure linux	TestAccept
3:51	gcp linux	TestAccept