tracking(workspace): complete Gitoxide workspace continuity

[Phoenix500526]

Problem

Maka has several independently verified Gitoxide and workspace-authority
foundations, but Phase 4 workspace continuity is not yet a product capability.
The remaining production composition—trusted packaged helper, state-root-owned
artifacts, filesystem projection, mutation acceptance, restore/rebaseline, and
Desktop/CLI workflows—is described across architecture documents without one
queryable tracker.

This issue tracks that existing Phase 4 route. It must not revive the removed
Git-executable managed-workspace path.

Design sources:

• Phase 3–4 implementation route
• Workspace Version Authority v1
• Gitoxide repository admission
• Gitoxide source import
• Gitoxide candidate/accepted-tree data plane
• Managed mutation lifecycle authority

Related foundations: #1743, #3561, #3741, and #3857. The retired path was
removed in #4174. Roadmap context: #544 and #2469.

Current baseline and remaining work

• Persist canonical workspace epoch/version/head facts and rebuildable schema 9 projections (Add canonical workspace baseline version authority #1743)
• Add bounded Gitoxide helper invocation, repository admission, and fresh source import (feat(git): establish Gitoxide repository admission and import #3561)
• Establish managed mutation T1/reservation/successor authority (feat(runtime): establish managed mutation lifecycle authority #3741)
• Add accepted-tree reads and operation-bound immutable candidates (feat(runtime-host): add Gitoxide candidate and accepted-tree read data plane #3857)
• Remove the dormant Git-executable write path (refactor: remove dormant Git workspace write path #4174)
• Bind the helper to a signed packaged-release trust root and protected installation path
• Add a storage-root-bound destination capability with durable receipt, quarantine, cleanup, and reopen ownership
• Compose Gitoxide baseline admission with the schema 9 workspace writer
• Define and enforce FilesystemMaterializationProfileV1
• Bind accepted capability and candidate outcome to mutation T1/T2, then promote or reconcile the accepted ref
• Reissue capabilities safely after Host restart and recover or collect stale candidates and partial artifacts
• Bind continuations to accepted workspace versions and implement isolated restore plus durable rebaseline facts
• Add Desktop/CLI workflows, rollout gates, metrics, and production-shaped platform tests

Non-goals

• Restoring the old Git CLI adapter or managed_worktree_v1 profile
• Resetting, cleaning, or overwriting an attached user checkout
• Treating a workspace UUID as proof of file contents
• Claiming unsupported filesystem semantics without a versioned policy
• Automatically retrying side effects whose outcome cannot be proven