complete cow school scripts

Move bash scripts under src/bash_scripts, add college/university/smart cow implementations, and mark the completed TODO items.

TODO.md

@@ -17,17 +17,17 @@
 
 ## 3. Bash Scripts
 
-- [ ] **`cow_kindergarten`**
-  - [ ] Cow says numbers 1 to 10, 1-second pause between each, sticks out tongue at the end.
-- [ ] **`cow_primaryschool`**
-  - [ ] Cow says numbers 1 to `n` (argument).
-- [ ] **`cow_highschool`**
-  - [ ] Cow says squares (1, 4, 9, ..., `n^2`) (argument).
-- [ ] **`cow_college`**
-  - [ ] Cow says Fibonacci sequence up to `n`.
-- [ ] **`cow_university`**
-  - [ ] Cow says prime numbers up to `n`.
-- [ ] **`smart_cow`**
+- [x] **`cow_kindergarten`**
+  - [x] Cow says numbers 1 to 10, 1-second pause between each, sticks out tongue at the end.
+- [x] **`cow_primaryschool`**
+  - [x] Cow says numbers 1 to `n` (argument).
+- [x] **`cow_highschool`**
+  - [x] Cow says squares (1, 4, 9, ..., `n^2`) (argument).
+- [x] **`cow_college`**
+  - [x] Cow says Fibonacci sequence up to `n`.
+- [x] **`cow_university`**
+  - [x] Cow says prime numbers up to `n`.
+- [x] **`smart_cow`**
   - [ ] Cow says a simple arithmetic expression (e.g., "3+11"), eyes show the result.
 - [ ] **`crazy_cow`**
   - [ ] Create a "crazy arithmetic cow" script with something unusual or complex.