fix(client): address PR #78 review comments

- Widen world_seed entropy from u32 to full u64 by combining two randi()
  calls (Hoshe warning #1)
- Persist world_seed to save directory and restore on resume_game() so
  loaded sessions maintain D-010 deterministic replay (Tyre warning #2)
- Constrain EntanglementConfig intrigue range based on flat value so
  mundane_ratio stays within D-029 spec [45,55]% (both reviewers)
- Remove dead VIS_PERIPHERAL constant and _grow_bounds() method
- Update test_client_p1 peripheral test for forward-only simplification
- Fix misleading exp_fade shader comment (filter_nearest = hard step)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/tests/test_client_p1.gd

@@ -55,7 +55,9 @@ func test_fog_visibility_forward_tile() -> void:
 
 
 func test_fog_visibility_peripheral_tile() -> void:
-	# P1 #4: Peripheral-sector tile writes VIS_PERIPHERAL (180) to _vis_bytes.
+	# P1 #4: Server simplified to forward-only (Sprint 22, #569). All visible
+	# tiles are now written as VIS_FORWARD regardless of visibility_sectors value.
+	# Peripheral sector is no longer a distinct visual state.
 	var fog = _get_fog_state()
 	if fog == null:
 		return
@@ -65,8 +67,8 @@ func test_fog_visibility_peripheral_tile() -> void:
 	GameState.visibility_sectors = {Vector2i(10, 8): "Peripheral"}
 	fog.update_from_state()
 	assert_that(fog._vis_bytes[8 * 64 + 10]).override_failure_message(
-		"Peripheral tile at (10,8) should be VIS_PERIPHERAL=%d" % FogState.VIS_PERIPHERAL
-	).is_equal(FogState.VIS_PERIPHERAL)
+		"All visible tiles write VIS_FORWARD after forward-only simplification"
+	).is_equal(FogState.VIS_FORWARD)
 	GameState.visible_positions.clear()
 	GameState.visibility_sectors.clear()