feat(directives): unified contracts surface — backbone (#128)

This is the backbone PR for the unified directive workflow. A directive
holds a sequence of contracts; each contract is a spec body whose
execution drives tasks in the directive's shared worktree. Lifecycle
(Lock & Start, queue scheduler, drag-reorder) lands in follow-ups.

What's in this PR:
- Migration adds `position` (queue order) and `merge_mode`
  (shared|own_pr) columns to directive_documents. The actual table
  rename is deferred — the legacy `contracts` table from the old
  contracts system still exists, and the rename collision waits for
  Phase 5 to drop legacy contracts.
- Repository: list orders by position; create assigns next-position;
  update accepts merge_mode; new reorder_directive_document_position
  shifts siblings inside a transaction.
- HTTP: endpoints aliased under /api/v1/directives/{id}/contracts and
  /api/v1/contracts/{id}/... with a new /contracts/{id}/reorder.
- Frontend: api types renamed `DirectiveContract*` (avoiding the
  legacy `Contract` type collision); document-directives.tsx imports
  via aliases so the rest of the file is untouched.

Internal struct + table names stay `DirectiveDocument` /
`directive_documents` until the legacy contracts cleanup.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

1 files changed, 14 insertions, 6 deletions

diff --git a/makima/src/server/mod.rs b/makima/src/server/mod.rs
index dd79ddf..68d3dea 100644
--- a/makima/src/server/mod.rs
+++ b/makima/src/server/mod.rs
@@ -214,27 +214,35 @@ pub fn make_router(state: SharedState) -> Router {
         )
         .route("/directives/{id}/dogs/{dog_id}/orders", get(directives::list_dog_orders))
         .route("/directives/{id}/dogs/{dog_id}/pick-up-orders", post(directives::pick_up_dog_orders))
-        // Directive document endpoints (multi-document directive contracts).
+        // Contract endpoints (the unified directive contracts surface).
+        // The handler module + DB column names are still
+        // "directive_documents" for now — the user-facing names ("contract"
+        // in URLs / structs / UI) are aligned here while the deeper rename
+        // waits for legacy contracts removal (Phase 5).
         .route(
-            "/directives/{directive_id}/documents",
+            "/directives/{directive_id}/contracts",
             get(directive_documents::list_documents)
                 .post(directive_documents::create_document),
         )
         .route(
-            "/directive-documents/{document_id}",
+            "/contracts/{document_id}",
             get(directive_documents::get_document)
                 .patch(directive_documents::update_document),
         )
         .route(
-            "/directive-documents/{document_id}/ship",
+            "/contracts/{document_id}/ship",
             post(directive_documents::ship_document),
         )
         .route(
-            "/directive-documents/{document_id}/archive",
+            "/contracts/{document_id}/archive",
             post(directive_documents::archive_document),
         )
         .route(
-            "/directive-documents/{document_id}/tasks",
+            "/contracts/{document_id}/reorder",
+            post(directive_documents::reorder_contract),
+        )
+        .route(
+            "/contracts/{document_id}/tasks",
             get(directive_documents::list_document_tasks),
         )
         // Order endpoints