feat(v3): restructure project + add complete frontend

- Restructure: move backend from new_project/ to backend/
- Add full React/TypeScript frontend (37 pages, 17 services, 16 type defs, 11 query hooks)
- Add docs/ with SRS specs, user stories, and workflow documentation
- Update .gitignore for new directory layout

Workflows implemented:
  WF1 User Signup, WF2 Placement Test, WF3 Exam Configuration,
  WF4 General English Exam, WF5 Course Generation,
  WF6 Entity Student Onboarding, AI Course Generation,
  Adaptive Learning Engine UI, White-Label Branding, Score Release

Made-with: Cursor

custom_addons/encoach_placement/services/cefr_mapper.py

@@ -0,0 +1,83 @@
+class CefrMapper:
+    """Maps IRT theta values to CEFR levels and IELTS band scores."""
+
+    THETA_TO_CEFR = [
+        (-4.0, -2.5, 'pre_a1'),
+        (-2.5, -1.5, 'a1'),
+        (-1.5, -0.5, 'a2'),
+        (-0.5, 0.5, 'b1'),
+        (0.5, 1.5, 'b2'),
+        (1.5, 2.5, 'c1'),
+        (2.5, 4.0, 'c2'),
+    ]
+
+    CEFR_TO_BAND = {
+        'pre_a1': 2.0,
+        'a1': 3.0,
+        'a2': 4.0,
+        'b1': 5.0,
+        'b2': 6.5,
+        'c1': 7.5,
+        'c2': 9.0,
+    }
+
+    CEFR_LABELS = {
+        'pre_a1': 'Pre-A1 (Beginner)',
+        'a1': 'A1 (Elementary)',
+        'a2': 'A2 (Pre-Intermediate)',
+        'b1': 'B1 (Intermediate)',
+        'b2': 'B2 (Upper-Intermediate)',
+        'c1': 'C1 (Advanced)',
+        'c2': 'C2 (Proficient)',
+    }
+
+    @staticmethod
+    def theta_to_cefr(theta):
+        for low, high, level in CefrMapper.THETA_TO_CEFR:
+            if low <= theta < high:
+                return level
+        return 'c2' if theta >= 2.5 else 'pre_a1'
+
+    @staticmethod
+    def theta_to_band(theta):
+        cefr = CefrMapper.theta_to_cefr(theta)
+        base_band = CefrMapper.CEFR_TO_BAND.get(cefr, 5.0)
+
+        for low, high, level in CefrMapper.THETA_TO_CEFR:
+            if level == cefr:
+                range_width = high - low
+                if range_width > 0:
+                    position = (theta - low) / range_width
+                else:
+                    position = 0.5
+
+                cefr_list = list(CefrMapper.CEFR_TO_BAND.keys())
+                idx = cefr_list.index(cefr)
+                next_band = CefrMapper.CEFR_TO_BAND.get(
+                    cefr_list[min(idx + 1, len(cefr_list) - 1)], base_band + 1.0
+                )
+
+                band = base_band + position * (next_band - base_band)
+                return round(band * 2) / 2
+
+        return base_band
+
+    @staticmethod
+    def band_to_cefr(band):
+        if band < 2.5:
+            return 'pre_a1'
+        if band < 3.5:
+            return 'a1'
+        if band < 4.5:
+            return 'a2'
+        if band < 5.5:
+            return 'b1'
+        if band < 7.0:
+            return 'b2'
+        if band < 8.0:
+            return 'c1'
+        return 'c2'
+
+    @staticmethod
+    def get_cefr_label(cefr_code):
+        return CefrMapper.CEFR_LABELS.get(cefr_code, cefr_code)