chore(openspec): archive windows-bun-residual-shim-lifecycle

[Drswith]

Summary

Archive completed OpenSpec change windows-bun-residual-shim-lifecycle after its implementation PR (#735) merged, syncing the accepted agent-uninstall and lifecycle-reconciliation deltas into openspec/specs/.

Living specs now require:

• a missing package-provider executable (spawn ENOENT / ENOTDIR) to be provider-unavailable, not inconclusive presence
• a leftover PATH hit under Bun's global bin (/.bun/bin/ after separator normalization) not to count as live ownership after bun conclusively reports the package absent
• Windows Bun uninstall cleanup of an unchanged {binary}.exe / {binary}.bunx pair, plus leftover-PATH guidance that names that pair

This PR is process-only (openspec/ paths). It does not add product-path KEEP comments or restore the archived change folder in the working tree.

Linked Artifacts

• Issue: [Bug]: qtx install pi fails with "could not determine the installed state" on bun-only Windows machines #733
• OpenSpec: windows-bun-residual-shim-lifecycle
• Discussion: follow-on to implementation PR fix: restore install after leftover Bun shims on Windows #735

Validation

• bun run openspec:validate
• bun run memory:check
• bun run lint
• bun run format:check
• bun run typecheck

bun run test is not applicable for behavior: this archive PR only deletes the completed OpenSpec change and applies accepted spec deltas. No src/, scripts, or package metadata changed.

Release Intent

• Release: not applicable - OpenSpec archive closure only

Release Summary

• Not applicable - OpenSpec archive closure does not produce a release entry. The user-facing Windows leftover-shim install/uninstall fix already shipped in fix: restore install after leftover Bun shims on Windows #735.

Docs Updated

• openspec/...

Scope Check

• I did not add a new ad hoc root-level Markdown file.
• I updated the relevant issue, ADR, spec, runbook, or captured the missing doc work as follow-up.
• I did not silently expand project scope without recording it explicitly.

Closure Check

• Working tree was clean before archive closure started.
• Branch was pushed and this PR is the active delivery artifact.
• OpenSpec change is already archived or queued for agent-driven archive closure.
• Release is not applicable, delegated to release automation, or verified.

Notes

• Generated by bun run openspec:archive-closure -- windows-bun-residual-shim-lifecycle --apply-specs. fix: restore install after leftover Bun shims on Windows #735 did not apply living specs, so this archive used --apply-specs rather than --skip-specs.
• The generated openspec/changes/archive/2026-09-08-windows-bun-residual-shim-lifecycle/ directory was removed rather than committed, matching chore(openspec): archive fix-upgrade-unresolved-latest-crash #707, chore(openspec): archive cli-core-upgrade-p6 #712, chore(openspec): archive cursor-version-probe-targeting #720, chore(openspec): archive lifecycle-engines-core-internal-l3 #726, and chore(openspec): archive lifecycle-barrel-core-internal-l4 #728. Git history remains the archaeology.
• Process-only classification: no src/ KEEP comment. Merge-gating CI MAY skip the full product test matrix while still publishing the required job contexts.
• Did not touch YAML, release-core.yml, protect-main, SDK surfaces, --json, aliases, exit codes, state v2, or receipts.
• Did not start [Bug]: Agent version shows "unknown" when --version probe fails even though the provider reports the exact installed version #734 or Track agent-catalog support backlog #134.
• Did not touch active or shelved changes release-one-line-delivery, release-pr-skip-human-heuristics, restore-managed-update-and-resume-releases, or windows-ci-advisory-merge-gate.
• Archive closure still waits on merge of this PR.