Revamp questionnaire, parallelize run-all, add new tasks

- Replace 6 compound Likert questions with 12 atomic ones grouped by
  dimension (syntax, expressiveness, data/IO, errors, overall); drop
  free-form question. Responses now stored as ints, not strings.
- Back-compat layer maps legacy keys to new dimensions so existing
  results still render.
- Parallelize run-all with ThreadPoolExecutor (configurable workers)
  and add a thread-safe min-request-interval rate limiter to the
  Anthropic provider.
- Add new tasks: path_normalizer, todo_manager, currency_converter,
  locale_weather_url, network_info_parser, url_normalizer.

tasks/pipeline/currency_converter.toml

@@ -0,0 +1,113 @@
+name = "currency_converter"
+category = "pipeline"
+mode = "convert"
+description = """
+A currency converter that reads conversion requests from stdin.
+Each line has the format: AMOUNT FROM TO RATE
+  - AMOUNT: a decimal number (e.g., 12.35)
+  - FROM: 3-letter currency code
+  - TO: 3-letter currency code
+  - RATE: the exchange rate from FROM's base to TO's base
+
+Some currencies are pegged to others at fixed rates:
+  BAM is pegged to EUR at 1.95583
+  BMD is pegged to USD at 1.0
+  BND is pegged to SGD at 1.0
+  DJF is pegged to USD at 177.721
+  PAB is pegged to USD at 1.0
+
+When a pegged currency is involved, the conversion must account for the
+peg coefficient. The formula is: result = amount * (rate / coef_from) * coef_to
+where coef is the peg ratio (1 if not pegged).
+
+Output one line per input: "AMOUNT FROM = RESULT TO" with RESULT
+computed using bc with scale=2.
+For invalid lines (wrong field count or non-numeric amount), output "ERROR: <original line>".
+"""
+
+bash_source = '''
+#!/bin/bash
+
+pegged_to() {
+  case "$1" in
+    BAM) echo "EUR:1.95583" ;;
+    BMD) echo "USD:1.0" ;;
+    BND) echo "SGD:1.0" ;;
+    DJF) echo "USD:177.721" ;;
+    PAB) echo "USD:1.0" ;;
+    *)   echo "NONE:1" ;;
+  esac
+}
+
+while IFS= read -r line || [[ -n "$line" ]]; do
+  # Skip empty lines
+  [[ -z "$line" ]] && continue
+
+  # Parse fields
+  set -- $line
+  if [[ $# -ne 4 ]]; then
+    echo "ERROR: $line"
+    continue
+  fi
+
+  amount=$1
+  from=$2
+  to=$3
+  rate=$4
+
+  # Validate amount is numeric
+  if [[ ! "$amount" =~ ^[0-9]+(\.[0-9]+)?$ ]]; then
+    echo "ERROR: $line"
+    continue
+  fi
+
+  # Validate rate is numeric
+  if [[ ! "$rate" =~ ^[0-9]+(\.[0-9]+)?$ ]]; then
+    echo "ERROR: $line"
+    continue
+  fi
+
+  # Get peg info
+  peg_from=$(pegged_to "$from")
+  coef_from=$(echo "$peg_from" | cut -d: -f2)
+
+  peg_to=$(pegged_to "$to")
+  coef_to=$(echo "$peg_to" | cut -d: -f2)
+
+  # Calculate: result = amount * (rate / coef_from) * coef_to
+  result=$(echo "scale=8; $amount * ($rate / $coef_from) * $coef_to" | bc)
+  result=$(printf "%.2f" "$result")
+
+  echo "$amount $from = $result $to"
+done
+'''
+
+[[test_cases]]
+description = "Standard conversion with direct rate"
+stdin = """100 USD EUR 0.92
+50 GBP JPY 188.50"""
+expected_stdout = """100 USD = 92.00 EUR
+50 GBP = 9425.00 JPY"""
+
+[[test_cases]]
+description = "Pegged currency conversions"
+stdin = """100 BAM USD 1.08
+200 BMD EUR 0.92
+50 USD DJF 1.0"""
+expected_stdout = """100 BAM = 55.22 USD
+200 BMD = 184.00 EUR
+50 USD = 8886.05 DJF"""
+
+[[test_cases]]
+description = "Invalid input lines"
+stdin = """abc EUR USD 0.92
+100 USD
+100 EUR USD 0.85"""
+expected_stdout = """ERROR: abc EUR USD 0.92
+ERROR: 100 USD
+100 EUR = 85.00 USD"""
+
+[[test_cases]]
+description = "Pegged-to-pegged conversion"
+stdin = "100 BAM BMD 1.08"
+expected_stdout = "100 BAM = 55.22 BMD"