feat: add logutil and jobs internal packages

Add centralized jobs scheduler and logutil package with ANSI colors and duration formatting.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

backend/internal/logutil/logutil.go

@@ -0,0 +1,70 @@
+// Package logutil provides ANSI-coloured logging helpers shared between the
+// job scheduler and the HTTP request logger. Both use the same colour scheme
+// and duration formatting so log output is consistent across components.
+package logutil
+
+import (
+	"fmt"
+	"os"
+	"time"
+)
+
+// noColor controls whether ANSI escape codes are emitted.
+// Set via the standard NO_COLOR environment variable (https://no-color.org).
+var noColor bool
+
+func init() {
+	_, noColor = os.LookupEnv("NO_COLOR")
+}
+
+// color returns the escape sequence when NO_COLOR is unset, empty otherwise.
+func color(seq string) string {
+	if noColor {
+		return ""
+	}
+	return seq
+}
+
+// Reset, Bold, Dim — ANSI escape codes for log formatting.
+// They are empty strings when NO_COLOR is set.
+var (
+	Reset   = color("\033[0m")
+	Bold    = color("\033[1m")
+	Dim     = color("\033[2m")
+	Cyan    = color("\033[36m")
+	Green   = color("\033[32m")
+	Red     = color("\033[31m")
+	Yellow  = color("\033[33m")
+	Magenta = color("\033[35m")
+
+	BoldGreen   = color("\033[32;1m")
+	BoldYellow  = color("\033[33;1m")
+	BoldRed     = color("\033[31;1m")
+	BoldBlue    = color("\033[34;1m")
+	BoldMagenta = color("\033[35;1m")
+)
+
+var (
+	DebugLvl = Cyan + "[DEBUG]" + Reset
+	WarnLvl  = Yellow + "[WARN] " + Reset
+	ErrorLvl = Red + "[ERROR]" + Reset
+)
+
+func ColoredDuration(d time.Duration) string {
+	switch {
+	case d < 500*time.Millisecond:
+		return Green + d.String() + Reset
+	case d < 5*time.Second:
+		return Yellow + d.String() + Reset
+	default:
+		return Red + d.String() + Reset
+	}
+}
+
+func ColoredRows(n int) string {
+	text := fmt.Sprintf("%d row", n)
+	if n != 1 {
+		text += "s"
+	}
+	return BoldBlue + text + Reset
+}