docs: document persistent Podman workspace workdir behavior change

[yvonnedevlinrh]

Context

PR unbound-force/unbound-force#535 fixes buildPersistentRunArgs() to set --workdir and the WORKSPACE environment variable for persistent Podman workspaces. This is the persistent-mode counterpart to the ephemeral fix in PR #123.

User-facing behavior change

Before: When using uf sandbox create --backend podman with persistent workspaces, OpenCode started in /workspace (the container root mount) rather than the project directory.

After: OpenCode now starts in /workspace/<project-name>, matching the behavior of ephemeral workspaces.

Documentation impact

Any documentation covering:

• Podman sandbox setup / persistent workspaces
• uf sandbox create usage
• Workspace directory structure or environment variables (WORKSPACE)

should reflect that persistent workspaces now correctly set the working directory to the project subdirectory on creation.

References

• Fix PR: fix(sandbox): set workdir for persistent Podman workspace so OpenCode starts in project directory unbound-force#535
• Original PR (superseded): fix(sandbox): set workdir for persistent Podman workspace so OpenCode starts in project directory unbound-force#222
• Prior ephemeral fix: fix: pass WORKSPACE env var so entrypoint sets correct project CWD unbound-force#123
• OpenSpec: openspec/changes/fix-sandbox-persistent-workdir/