Remove input files and task descriptions from git tracking

- Add patterns to .gitignore for inputs directories and task description files
- Remove all input files and backstory files from git tracking (kept locally)
- Per Advent of Code rules, these should not be stored in version control

Author: ZoltePudeleczko

.gitignore

@@ -178,4 +178,14 @@ Cargo.lock
 
 *.exe
 
-obj/
+obj/
+
+# Advent of Code - Input files and task descriptions
+# Per AoC rules, these should not be stored in version control
+**/inputs/
+**/input*.txt
+**/input*.in
+**/*backstory*.txt
+**/example*.txt
+**/*example*.txt
+**/*example*.in