tests: fix suite-wide collection and failures

- config: switch Settings to ConfigDict(extra='ignore') so extra env vars
  (spoonacular_api_key, SWIFTLY_BEARER_TOKEN) don't crash import.
  Remove deprecated class Config.
- email: wrap SendGrid imports in try/except so the module loads without
  the optional dependency. Update test_email_backend to patch Mail/RepyTo.
- planner_select: default PlannerConfig.set_size=21 (3 meals/day × 7) is
  way too large for the unit test assertion that checks 3-recipe diversity.
  Introduced _CFG_3 with set_size=3 and applied to all tests.
- Delete stale test_matcher.py importing removed functions.

Full suite: 46 passed, 74 skipped (Postgres), 0 failed, 120 collected.

backend/tests/test_planner_select.py

@@ -7,6 +7,10 @@ from app.services.planner.types import RecipeCost, ScoredRecipe
 
 
 _CFG = PlannerConfig()
+_CFG_3 = PlannerConfig(w_savings=0.30, w_coverage=0.25, w_pantry=0.10, w_time=0.15, w_recency=0.20,
+                       set_size=3, top_k=20, p_protein=0.15, p_cuisine=0.10, recency_weeks=4,
+                       calorie_tolerance_pct=20, max_total_minutes=45, max_meal_cost=30.00,
+                       time_ideal_minutes=25, time_full_minutes=45, recency_full_weeks=12)
 
 
 def _mk(score, protein, cuisine):
@@ -34,7 +38,7 @@ def test_diversity_penalty_zero_when_all_unique():
     a = _mk(0.5, "chicken", "american")
     b = _mk(0.5, "beef", "mexican")
     c = _mk(0.5, "fish", "italian")
-    assert set_diversity_penalty([a, b, c], _CFG) == 0.0
+    assert set_diversity_penalty([a, b, c], _CFG_3) == 0.0
 
 
 def test_diversity_penalty_three_chickens():
@@ -42,7 +46,7 @@ def test_diversity_penalty_three_chickens():
     b = _mk(0.5, "chicken", "italian")
     c = _mk(0.5, "chicken", "mexican")
     # 3 protein pairs * 0.15 = 0.45, no cuisine pairs
-    p = set_diversity_penalty([a, b, c], _CFG)
+    p = set_diversity_penalty([a, b, c], _CFG_3)
     assert abs(p - 0.45) < 1e-6
 
 
@@ -60,7 +64,7 @@ def test_select_set_picks_diverse_over_homogeneous():
     mix2 = _mk(0.90, "chicken", "mexican")    # shares protein with high
     mix3 = _mk(0.90, "fish", "american")      # shares cuisine with high
 
-    chosen, set_score = select_set([high1, high2, high3, mix1, mix2, mix3], _CFG)
+    chosen, set_score = select_set([high1, high2, high3, mix1, mix2, mix3], _CFG_3)
     chosen_ids = {s.recipe_id for s in chosen}
     assert chosen_ids == {mix1.recipe_id, mix2.recipe_id, mix3.recipe_id}
 
@@ -68,11 +72,11 @@ def test_select_set_picks_diverse_over_homogeneous():
 def test_select_set_handles_too_few():
     a = _mk(0.5, "x", "y")
     b = _mk(0.5, "x", "y")
-    chosen, _ = select_set([a, b], _CFG)
+    chosen, _ = select_set([a, b], _CFG_3)
     assert len(chosen) == 2  # less than set_size returns what we have
 
 
 def test_select_set_empty_input():
-    chosen, score = select_set([], _CFG)
+    chosen, score = select_set([], _CFG_3)
     assert chosen == []
     assert score == 0.0