Fix Rust VM create and gui regressions

[rysweet]

Summary

• restore correct azlin-session tagging for named single-VM creates
• seed named single-VM creates from local ~/.azlin/home/ during create
• bound azlin gui dependency setup via routed non-interactive SSH with explicit failure reporting
• add merge-readiness docs and targeted gadugi regression coverage for the named-create and GUI fixes

Merge readiness

QA-team evidence

• Scenario files: tests/agentic-scenarios/pr-939-regression-coverage.yaml
• Validation command: gadugi-test validate -f tests/agentic-scenarios/pr-939-regression-coverage.yaml
• Validation result: passed
• Run command: gadugi-test run -d tests/agentic-scenarios -s pr-939-regression-coverage --timeout 900000
• Run target: local env
• Run result: passed (Passed: 1, Failed: 0)
• Evidence location: this section, /tmp/pr-939-gadugi-validate.log, /tmp/pr-939-gadugi-run.log, and /home/rysweet/src/azlin/worktrees/retry/issue-938-fix-these-three-rust-regressions-in-azlin-and-vali/outputs/sessions/session_5584856c-b3e7-4ca9-9d1b-8823f220d0cc_2026-04-04T14-57-47-809Z.json

RESOLVE_SESSION_IDENTITY_OK
SEED_REMOTE_HOME_OK
BUILD_ROUTED_SSH_TRANSPORT_OK
DEPENDENCY_SETUP_OK
RESOLVE_GUI_TARGET_USER_OK
Passed: 1
Failed: 0
All tests passed!

Documentation

• User-facing docs impact: yes
• Updated docs: README.md, docs-site/commands/vm/new.md, docs/reference/credential-forwarding.md, docs-site/advanced/gui-forwarding.md, docs/GUI_FORWARDING.md
• PR description links added: README.md, docs-site/commands/vm/new.md, docs/reference/credential-forwarding.md, docs-site/advanced/gui-forwarding.md, docs/GUI_FORWARDING.md
• Rationale if not applicable: n/a

Quality-audit

• Cycle 1 summary: merge-ready review found missing QA evidence, missing user-facing docs for azlin new --name / azlin gui, and incomplete PR evidence. Fixes: added a targeted gadugi regression scenario and updated the user-facing docs that describe named create/session-tag behavior and GUI setup behavior.
• Cycle 2 summary: the first gadugi run exposed a false-positive risk because the initial scenario used tail -20 plus cargo summaries, which could pass without proving the targeted tests ran. Fixes: tightened the scenario to grep for the exact regression test names and reran validate/run successfully.
• Cycle 3 summary: a final high-signal review pass over the updated diff found no significant issues; docs matched the Rust implementation and the QA scenario proved the intended regression tests.
• Additional cycles: none
• Final clean cycle: 3
• Fixes followed default-workflow: yes
• Convergence summary: the original merge-readiness blockers are closed, the scenario evidence is real, the docs now describe the changed behavior, CI is green, and the final review cycle was clean.

CI

• Checks command: gh pr checks 939
• Result: all green
• Skipped checks: Security Scanning/OSSF Scorecard (skipped by workflow configuration on pull_request)
• Flaky reruns performed: none
• Real failures fixed: none

Scope

• Changed files reviewed: gh pr diff 939 --name-only
• Unrelated changes: none

Verdict

• Merge-ready: yes
• Remaining blockers: none