feat(11-01): schema, service, and tests for sort_order + reorderCandidates

- Add sortOrder REAL column to threadCandidates schema (default 0)
- Add sort_order column to test helper CREATE TABLE
- Add reorderCandidatesSchema to shared/schemas.ts
- Add ReorderCandidates type to shared/types.ts
- getThreadWithCandidates now orders candidates by sort_order ASC
- createCandidate appends at max sort_order + 1000 (first = 1000)
- Add reorderCandidates service function (transaction, active-only guard)
- Add 5 new tests: ordering, appending, reorder success, resolved guard, missing thread

src/shared/types.ts

@@ -13,6 +13,7 @@ import type {
 	createItemSchema,
 	createSetupSchema,
 	createThreadSchema,
+	reorderCandidatesSchema,
 	resolveThreadSchema,
 	syncSetupItemsSchema,
 	updateCandidateSchema,
@@ -33,6 +34,7 @@ export type UpdateThread = z.infer<typeof updateThreadSchema>;
 export type CreateCandidate = z.infer<typeof createCandidateSchema>;
 export type UpdateCandidate = z.infer<typeof updateCandidateSchema>;
 export type ResolveThread = z.infer<typeof resolveThreadSchema>;
+export type ReorderCandidates = z.infer<typeof reorderCandidatesSchema>;
 
 // Setup types
 export type CreateSetup = z.infer<typeof createSetupSchema>;