Jelly, 13 bytes
Encode, 7 bytes
1,0ṁx‘Ḅ
Decode, 6 bytes
ȯIBŒɠ’
Encodes positive integers in the run lengths of the binary representation. Since we may have zeros, we increment all numbers. For example, the list [0,1,4] is encoded as 10011111 in binary.
Numbers from 0 to 100 (Try it online!):
0 []
1 [0]
2 [0, 0]
3 [1]
4 [0, 1]
5 [0, 0, 0]
6 [1, 0]
7 [2]
8 [0, 2]
9 [0, 1, 0]
10 [0, 0, 0, 0]
11 [0, 0, 1]
12 [1, 1]
13 [1, 0, 0]
14 [2, 0]
15 [3]
16 [0, 3]
17 [0, 2, 0]
18 [0, 1, 0, 0]
19 [0, 1, 1]
20 [0, 0, 0, 1]
21 [0, 0, 0, 0, 0]
22 [0, 0, 1, 0]
23 [0, 0, 2]
24 [1, 2]
25 [1, 1, 0]
26 [1, 0, 0, 0]
27 [1, 0, 1]
28 [2, 1]
29 [2, 0, 0]
30 [3, 0]
31 [4]
32 [0, 4]
33 [0, 3, 0]
34 [0, 2, 0, 0]
35 [0, 2, 1]
36 [0, 1, 0, 1]
37 [0, 1, 0, 0, 0]
38 [0, 1, 1, 0]
39 [0, 1, 2]
40 [0, 0, 0, 2]
41 [0, 0, 0, 1, 0]
42 [0, 0, 0, 0, 0, 0]
43 [0, 0, 0, 0, 1]
44 [0, 0, 1, 1]
45 [0, 0, 1, 0, 0]
46 [0, 0, 2, 0]
47 [0, 0, 3]
48 [1, 3]
49 [1, 2, 0]
50 [1, 1, 0, 0]
51 [1, 1, 1]
52 [1, 0, 0, 1]
53 [1, 0, 0, 0, 0]
54 [1, 0, 1, 0]
55 [1, 0, 2]
56 [2, 2]
57 [2, 1, 0]
58 [2, 0, 0, 0]
59 [2, 0, 1]
60 [3, 1]
61 [3, 0, 0]
62 [4, 0]
63 [5]
64 [0, 5]
65 [0, 4, 0]
66 [0, 3, 0, 0]
67 [0, 3, 1]
68 [0, 2, 0, 1]
69 [0, 2, 0, 0, 0]
70 [0, 2, 1, 0]
71 [0, 2, 2]
72 [0, 1, 0, 2]
73 [0, 1, 0, 1, 0]
74 [0, 1, 0, 0, 0, 0]
75 [0, 1, 0, 0, 1]
76 [0, 1, 1, 1]
77 [0, 1, 1, 0, 0]
78 [0, 1, 2, 0]
79 [0, 1, 3]
80 [0, 0, 0, 3]
81 [0, 0, 0, 2, 0]
82 [0, 0, 0, 1, 0, 0]
83 [0, 0, 0, 1, 1]
84 [0, 0, 0, 0, 0, 1]
85 [0, 0, 0, 0, 0, 0, 0]
86 [0, 0, 0, 0, 1, 0]
87 [0, 0, 0, 0, 2]
88 [0, 0, 1, 2]
89 [0, 0, 1, 1, 0]
90 [0, 0, 1, 0, 0, 0]
91 [0, 0, 1, 0, 1]
92 [0, 0, 2, 1]
93 [0, 0, 2, 0, 0]
94 [0, 0, 3, 0]
95 [0, 0, 4]
96 [1, 4]
97 [1, 3, 0]
98 [1, 2, 0, 0]
99 [1, 2, 1]
100 [1, 1, 0, 1]