feat(missions): mission board — schema, deterministic generation, top-up + v6 backfill

New missions table (schema + DDL). Pure model in lib/game/missions.ts:
DELIVER / EXPLORE / FIND contracts generated from missionRng(seed, turn),
board always topped up to >=3 AVAILABLE after every action. save.ts wires
SCHEMA_VERSION 5 -> 6 with a v6 backfill step and completion hooks inside
jumpToSystem/explorePlanet (one atomic persist). Unit tests cover generation
determinism, top-up idempotency, backfill, accept validation and per-type
completion incl. reward accumulation.

lib/db/schema.ts

@@ -108,6 +108,24 @@ export const tech = sqliteTable(
   (t) => [uniqueIndex('tech_save_slug_unique').on(t.saveId, t.slug)],
 )
 
+// The mission board (#10): contracts generated deterministically from the save seed, one ACTIVE
+// at a time. `type` drives completion semantics (see advanceMission in lib/game/missions.ts):
+// DELIVER jumps to target_system_id, EXPLORE counts scans up to progress_target, FIND completes
+// when a scan's haul contains condition_kind. The reward lands in inventory_items on completion.
+export const missions = sqliteTable('missions', {
+  id: integer('id').primaryKey({ autoIncrement: true }),
+  saveId: integer('save_id').notNull().references(() => saves.id),
+  type: text('type').notNull(), // 'DELIVER' | 'EXPLORE' | 'FIND'
+  description: text('description').notNull(), // human-readable objective, e.g. "Jump to Kepler Drift"
+  targetSystemId: integer('target_system_id'), // DELIVER only — destination system (NULL otherwise)
+  conditionKind: text('condition_kind'), // FIND only — 'resource' | 'part' (NULL otherwise)
+  progressTarget: integer('progress_target').notNull().default(1), // EXPLORE: scans required; 1 for the others
+  progress: integer('progress').notNull().default(0), // scans counted since acceptance; 0/1 for DELIVER/FIND
+  rewardKind: text('reward_kind').notNull(), // 'resource' | 'part'
+  rewardQty: integer('reward_qty').notNull().default(1),
+  state: text('state').notNull().default('AVAILABLE'), // 'AVAILABLE' | 'ACTIVE' | 'DONE'
+})
+
 // Append-only game log. Writers so far: new-game + jump events; later issues add more
 // writers and a read endpoint.
 export const events = sqliteTable('events', {