Supported Patch Inverse Planning

PR-026 adds read-only inverse planning for the supported patch-operation subset.

prikk inverse-plan [path] [--ref REF]

--ref takes any published ref, not only a branch. A tag ref resolves through its tag object to the Block that object names, so prikk inverse-plan --ref tags/v1 plans the inverse of the tagged Block’s patch, which need not be the branch tip. The same is true of prikk rollback-preview and prikk rollback-draft-verify, which reach the same resolution. prikk rollback-draft --append-inverse still requires a branch ref: it appends to that ref’s active WAL, and a tag names no WAL.

The command walks the same single-parent sealed block chain used by supported patch replay. While validating and replaying the chain, Prikk derives an unsigned inverse Patch payload in reverse application order.

Supported inverse shapes in PR-026:

• CreateFile → inverse DeleteFile
• DeleteFile → inverse CreateFile

Safety boundaries:

• The command is read-only.
• The inverse Patch is not written to the object store.
• The reported inverse Patch ID is only an unsigned deterministic planning hint.
• EditText direct inverse for arbitrary spans remains deferred until the required round-trip vectors land.
• Rollback refs, authorization policy, conflict witnesses, commutation, and confluence remain later increments.