Reorganize task categories from opaque a/b to descriptive names

Replace category_a/category_b directories with algorithm, pipeline,
environment, filesystem, and process. Add separate mode field (solve/convert)
to decouple orchestration from capability grouping. Add per-category
summary and questionnaire breakdowns to both terminal report and HTML export.

tasks/algorithm/fizzbuzz.toml

@@ -0,0 +1,39 @@
+name = "fizzbuzz"
+category = "algorithm"
+mode = "solve"
+description = """
+Read a single integer N from stdin. Print numbers from 1 to N, one per line.
+For multiples of 3, print "Fizz" instead of the number.
+For multiples of 5, print "Buzz" instead of the number.
+For multiples of both 3 and 5, print "FizzBuzz" instead of the number.
+"""
+
+[[test_cases]]
+stdin = "15"
+expected_stdout = """1
+2
+Fizz
+4
+Buzz
+Fizz
+7
+8
+Fizz
+Buzz
+11
+Fizz
+13
+14
+FizzBuzz"""
+
+[[test_cases]]
+stdin = "5"
+expected_stdout = """1
+2
+Fizz
+4
+Buzz"""
+
+[[test_cases]]
+stdin = "1"
+expected_stdout = "1"

tasks/algorithm/reverse_string.toml

@@ -0,0 +1,22 @@
+name = "reverse_string"
+category = "algorithm"
+mode = "solve"
+description = """
+Read a single line from stdin and print it reversed to stdout.
+"""
+
+[[test_cases]]
+stdin = "hello"
+expected_stdout = "olleh"
+
+[[test_cases]]
+stdin = "abcdef"
+expected_stdout = "fedcba"
+
+[[test_cases]]
+stdin = "racecar"
+expected_stdout = "racecar"
+
+[[test_cases]]
+stdin = "a"
+expected_stdout = "a"

tasks/algorithm/two_sum.toml

@@ -0,0 +1,25 @@
+name = "two_sum"
+category = "algorithm"
+mode = "solve"
+description = """
+Read input from stdin. The first line contains a target integer.
+The second line contains space-separated integers (the array).
+Find two indices (0-based) such that the numbers at those indices add up to the target.
+Print the two indices on a single line, space-separated, smaller index first.
+There is exactly one solution.
+"""
+
+[[test_cases]]
+stdin = """9
+2 7 11 15"""
+expected_stdout = "0 1"
+
+[[test_cases]]
+stdin = """6
+3 2 4"""
+expected_stdout = "1 2"
+
+[[test_cases]]
+stdin = """6
+3 3"""
+expected_stdout = "0 1"