fix(worksheets): validation function was converting mastery mode to manual

CRITICAL FIX: The validateWorksheetConfig() function only checked for mode === 'smart',
causing mastery mode configs to fall through to the manual mode path. This meant:
- Frontend sent mode: 'mastery' with displayRules
- Validation function created a manual mode config instead
- displayRules were lost, replaced with boolean flags
- Ten-frames didn't render because flags defaulted to false

Changes:
- validation.ts: Check for both 'smart' OR 'mastery' when using displayRules
- validation.ts: Preserve mode as 'smart' | 'mastery' instead of forcing 'smart'
- validation.ts: Include currentStepId for mastery progression tracking
- types.ts: Import and include AdditionConfigV4Mastery in WorksheetFormState type

This was the third place mastery mode needed to be handled:
1. ✅ config-schemas.ts - Zod schema (added in previous commit)
2. ✅ typstGenerator.ts - Problem enrichment (added in previous commit)
3. ✅ validation.ts - Config validation (this commit)

Tests: All 14 ten-frames tests passing

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/web/.claude/settings.local.json

@@ -36,7 +36,9 @@
       "Bash(done)",
       "mcp__sqlite__list_tables",
       "mcp__sqlite__describe_table",
-      "Bash(npm test:*)"
+      "Bash(npm test:*)",
+      "mcp__sqlite__read_query",
+      "Bash(cat:*)"
     ],
     "deny": [],
     "ask": []

apps/web/src/app/create/worksheets/addition/types.ts

@@ -4,6 +4,7 @@ import type {
   AdditionConfigV4,
   AdditionConfigV4Smart,
   AdditionConfigV4Manual,
+  AdditionConfigV4Mastery,
 } from '../config-schemas'
 
 /**
@@ -42,26 +43,25 @@ export type WorksheetConfig = AdditionConfigV4 & {
  * Partial form state - user may be editing, fields optional
  * Based on V4 config with additional derived state
  *
- * V4 supports two modes via discriminated union:
+ * V4 supports three modes via discriminated union:
  * - Smart mode: Has displayRules and optional difficultyProfile
+ * - Mastery mode: Has displayRules and optional currentStepId
  * - Manual mode: Has boolean display flags and optional manualPreset
  *
  * During editing, mode field may be present to indicate which mode is active.
  * If mode is absent, defaults to 'smart' mode.
  *
  * This type is intentionally permissive during form editing to allow fields from
- * both modes to exist temporarily. Validation will enforce mode consistency.
+ * all modes to exist temporarily. Validation will enforce mode consistency.
  */
 export type WorksheetFormState = Partial<Omit<AdditionConfigV4Smart, 'version'>> &
-  Partial<Omit<AdditionConfigV4Manual, 'version'>> & {
+  Partial<Omit<AdditionConfigV4Manual, 'version'>> &
+  Partial<Omit<AdditionConfigV4Mastery, 'version'>> & {
     // DERIVED state (calculated from primary state)
     rows?: number
     total?: number
     date?: string
     seed?: number
-
-    // Mastery progression mode
-    currentStepId?: string // Current step in progression path
   }
 
 /**

apps/web/src/app/create/worksheets/addition/validation.ts

@@ -138,8 +138,8 @@ export function validateWorksheetConfig(formState: WorksheetFormState): Validati
   // Build mode-specific config
   let config: WorksheetConfig
 
-  if (mode === 'smart') {
+  if (mode === 'smart' || mode === 'mastery') {
-    // Smart mode: Use displayRules for conditional scaffolding
+    // Smart & Mastery modes: Use displayRules for conditional scaffolding
     const displayRules: DisplayRules = {
       carryBoxes: 'whenRegrouping',
       answerBoxes: 'always',
@@ -154,9 +154,10 @@ export function validateWorksheetConfig(formState: WorksheetFormState): Validati
 
     config = {
       version: 4,
-      mode: 'smart',
+      mode: mode as 'smart' | 'mastery', // Preserve the actual mode
       displayRules,
       difficultyProfile: formState.difficultyProfile,
+      currentStepId: formState.currentStepId, // Mastery progression tracking
       ...sharedFields,
     }
   } else {