feat(contracts): lifecycle — Lock/Start/Pause/Complete/Unlock + queue schedulercontract-lifecycle

Adds the contract lifecycle layer on top of the unified-contracts
backbone (#128). State machine:

    draft → queued → active → shipped → archived

At most one contract per directive sits in `active` at any time —
the queue is serialised because each directive owns a single shared
worktree. Repository helpers handle the transition checks AND
auto-promote the next-up `queued` contract whenever the active slot
frees (pause / complete / unlock-from-active / archive-from-active).

Endpoints (all under /api/v1/contracts/{id}):
  POST /start    draft → queued | active (depending on slot)
  POST /pause    active → queued; promotes next queued
  POST /complete active → shipped; optional pr_url + pr_branch
  POST /unlock   queued | active → draft; promotes if was active

Frontend wiring:
  * `DirectiveContractStatus` now includes `queued`.
  * Migration adds `queued` to the CHECK constraint on
    directive_documents.status.
  * `ContractHeader` component renders breadcrumb + status pill +
    status-driven action buttons + a merge-mode (shared / own_pr)
    radio. Merge mode is editable only while draft / queued so a
    running flow's branch target can't change mid-stream.
  * RepositoryError gains a `Validation(String)` arm; the three
    existing exhaustive matches (files, mesh, versions) get a
    400 BAD_REQUEST response for it.

Drag-to-reorder UI deferred to a small follow-up — the backend
endpoint already exists from the backbone PR.

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

1 files changed, 16 insertions, 0 deletions

diff --git a/makima/src/server/mod.rs b/makima/src/server/mod.rs
index 68d3dea..a3a1886 100644
--- a/makima/src/server/mod.rs
+++ b/makima/src/server/mod.rs
@@ -242,6 +242,22 @@ pub fn make_router(state: SharedState) -> Router {
             post(directive_documents::reorder_contract),
         )
         .route(
+            "/contracts/{document_id}/start",
+            post(directive_documents::start_contract),
+        )
+        .route(
+            "/contracts/{document_id}/pause",
+            post(directive_documents::pause_contract),
+        )
+        .route(
+            "/contracts/{document_id}/complete",
+            post(directive_documents::complete_contract),
+        )
+        .route(
+            "/contracts/{document_id}/unlock",
+            post(directive_documents::unlock_contract),
+        )
+        .route(
             "/contracts/{document_id}/tasks",
             get(directive_documents::list_document_tasks),
         )