Wolves with a den, fishing, and a mixed diet

Wolves
- Den: a boulder cave at the foot of the rim, sited from the seed (away
  from the sea and spawn, mouth toward the valley, clearing in front)
- Grace period: no wolves days 1-2; they move in on day 3 and howl; hunting
  from night 4; pack of 2, 3 from day 6, 4 from day 9; replaced by day
- Wary pack hunters: circle and dart in one at a time; a lit campfire is a
  safe zone, a torch makes them hesitate, walls block bites (line of
  sight); hit one and the pack turns; hurt wolves flee; a lone wolf is
  timid; by day they defend the den; home at dawn
- Glowing eyes, synthesised howls, can't sleep with wolves prowling
- Wolf pelt and Wolf Cloak (+25 warmth)
- Animals take a committed detour around obstacles

Fishing
- Fishing rod (workbench); cast a float onto the lake, 1.5 s to land a bite
- Perch and rarer trout; faster bites at dawn/dusk and in rain; grill them
- Visible fish near the shore that jump with splash rings

Mixed diet
- Foods belong to meat, fish or greens; each level runs down over ~1.5 days
- One group low: no healing; two low: Malnourished (health drains);
  all three good: Balanced diet (heal x1.5); HUD diet bars; saved

Tests: test_wolves and test_fishing_diet; run_all.sh covers 9 suites

docs/ROADMAP.md

@@ -33,7 +33,9 @@ Detailed plan in `docs/SURVIVAL_DESIGN.md` (phases M1a–M1d).
 - [x] Snap-together building: floor/wall/door/roof/gable, resource cost, support + collapse, dismantling *(M1c)*
 - [x] Bed spawn point and sleeping, resource regrowth *(M1c)*
 - [x] Creatures (rabbit, deer, boar), hunting, club/spear/bow, butchering, cooked-food buffs, hide cloak *(M1d)*
-- [ ] Wolves at night, hide armour, more recipes *(later M1 polish)*
+- [x] Wolves at night with a den and a 3-day grace period, wolf cloak *(M1e)*
+- [x] Fishing (rod, perch and trout, grilling) and a mixed diet *(M1e)*
+- [ ] Hide armour, more recipes, sea fishing *(later M1 polish)*
 - **Done when:** gather → craft → build a tiny shelter, single-player.
 
 ## M2 — Multiplayer · ~2–4 months