Implement urgency system with TaskWarrior-inspired calculation

- Add urgency calculation based on multiple factors:
  * Due date (linear scale: overdue=12.0, today=10.0, week=6.0, 2weeks=2.0)
  * Priority (H=6.0, M=3.9, D=1.8, L=0.0)
  * Age (0-2.0 over 365 days)
  * Active status (+4.0 boost)
  * Waiting status (-3.0 penalty)
  * Tags (+1.0 with count modifier)
  * Project assignment (+1.0)
  * Configurable urgent tag (default 'next', +15.0)

- Replace priority column with urgency in all reports
  * Display as decimal with 1 decimal place
  * 4-tier color coding: ≥10 (bright red), ≥5 (red), ≥2 (yellow), <2 (cyan)
  * Minimal format color-coded by urgency

- Add default urgency sorting to all reports
  * list, minimal, active, ready, overdue reports sort by urgency
  * newest/oldest keep date-based sorting

- Implement 'next' report
  * Shows most urgent ready tasks
  * Configurable limit (default 5)
  * Only includes tasks ready to work on (no future wait/scheduled)

- Add urgency display to info command
  * Shows urgency score alongside priority

- All urgency coefficients configurable via config
  * Adjusted defaults for Opal's simpler model (no blocking/annotations)
  * Configurable urgent tag name (not hardcoded to 'next')

Priority order maintained: High > Medium > Default > Low

opal-task/internal/engine/report.go

@@ -31,6 +31,7 @@ func AllReports() map[string]*Report {
 		"list":      ListReport(),
 		"minimal":   MinimalReport(),
 		"newest":    NewestReport(),
+		"next":      NextReport(),
 		"oldest":    OldestReport(),
 		"overdue":   OverdueReport(),
 		"ready":     ReadyReport(),
@@ -61,6 +62,7 @@ func ActiveReport() *Report {
 		Description:   "Started tasks",
 		BaseFilter:    filter,
 		DisplayFormat: DisplayFormatTable,
+		SortFunc:      sortByUrgency,
 	}
 }
 
@@ -100,6 +102,7 @@ func ListReport() *Report {
 		Description:   "Pending tasks",
 		BaseFilter:    filter,
 		DisplayFormat: DisplayFormatTable,
+		SortFunc:      sortByUrgency,
 	}
 }
 
@@ -113,6 +116,7 @@ func MinimalReport() *Report {
 		Description:   "Pending tasks (minimal format)",
 		BaseFilter:    filter,
 		DisplayFormat: DisplayFormatMinimal,
+		SortFunc:      sortByUrgency,
 	}
 }
 
@@ -148,6 +152,51 @@ func NewestReport() *Report {
 	}
 }
 
+// NextReport shows most urgent tasks ready to work on
+func NextReport() *Report {
+	filter := NewFilter()
+	filter.Attributes["status"] = "pending"
+	filter.Attributes["_ready"] = "true"
+
+	return &Report{
+		Name:          "next",
+		Description:   "Most urgent tasks ready to work on",
+		BaseFilter:    filter,
+		DisplayFormat: DisplayFormatTable,
+		SortFunc: func(tasks []*Task) []*Task {
+			// Sort by urgency descending
+			cfg, _ := GetConfig()
+			coeffs := BuildUrgencyCoefficients(cfg)
+
+			sorted := make([]*Task, len(tasks))
+			copy(sorted, tasks)
+
+			for i := 0; i < len(sorted)-1; i++ {
+				for j := i + 1; j < len(sorted); j++ {
+					urgI := sorted[i].CalculateUrgency(coeffs)
+					urgJ := sorted[j].CalculateUrgency(coeffs)
+					if urgI < urgJ {
+						sorted[i], sorted[j] = sorted[j], sorted[i]
+					}
+				}
+			}
+
+			return sorted
+		},
+		LimitFunc: func(tasks []*Task) []*Task {
+			cfg, _ := GetConfig()
+			limit := cfg.NextLimit
+			if limit <= 0 {
+				limit = 5
+			}
+			if len(tasks) > limit {
+				return tasks[:limit]
+			}
+			return tasks
+		},
+	}
+}
+
 // OldestReport shows oldest pending tasks
 func OldestReport() *Report {
 	filter := NewFilter()
@@ -185,6 +234,7 @@ func OverdueReport() *Report {
 		Description:   "Overdue tasks",
 		BaseFilter:    filter,
 		DisplayFormat: DisplayFormatTable,
+		SortFunc:      sortByUrgency,
 	}
 }
 
@@ -199,6 +249,7 @@ func ReadyReport() *Report {
 		Description:   "Tasks ready to work on",
 		BaseFilter:    filter,
 		DisplayFormat: DisplayFormatTable,
+		SortFunc:      sortByUrgency,
 	}
 }
 
@@ -368,3 +419,24 @@ func mergeFilters(base, user *Filter) *Filter {
 
 	return merged
 }
+
+// sortByUrgency is a helper function to sort tasks by urgency (descending)
+func sortByUrgency(tasks []*Task) []*Task {
+	cfg, _ := GetConfig()
+	coeffs := BuildUrgencyCoefficients(cfg)
+
+	sorted := make([]*Task, len(tasks))
+	copy(sorted, tasks)
+
+	for i := 0; i < len(sorted)-1; i++ {
+		for j := i + 1; j < len(sorted); j++ {
+			urgI := sorted[i].CalculateUrgency(coeffs)
+			urgJ := sorted[j].CalculateUrgency(coeffs)
+			if urgI < urgJ {
+				sorted[i], sorted[j] = sorted[j], sorted[i]
+			}
+		}
+	}
+
+	return sorted
+}