feat(ux): visual improvements for list tree, graph, and show commands

bd list --tree:
- Use actual parent-child dependencies instead of dotted ID hierarchy
- Treat epic dependencies as parent-child relationships
- Sort children by priority (P0 first)
- Fix tree display in daemon mode with read-only store access

bd graph:
- Add --all flag to show dependency graph of all open issues
- Add --compact flag for tree-style rendering (reduces 44+ lines to 13)
- Fix "needs:N" cognitive noise by using semantic colors
- Add blocks:N indicator with semantic red coloring

bd show:
- Tufte-aligned header with status icon, priority, and type badges
- Add glamour markdown rendering with auto light/dark mode detection
- Cap markdown line width at 100 chars for readability
- Mute entire row for closed dependencies (work done, no attention needed)

Design system:
- Add shared status icons (○ ◐ ● ✓ ❄) with semantic colors
- Implement priority colors: P0 red, P1 orange, P2 muted gold, P3-P4 neutral
- Add TrueColor profile for distinct hex color rendering
- Type badges for epic (purple) and bug (red)

Design principles:
- Semantic colors only for actionable items
- Closed items fade (muted gray)
- Icons > text labels for better scanability

Co-Authored-By: SageOx <ox@sageox.ai>

internal/ui/markdown.go

@@ -0,0 +1,54 @@
+// Package ui provides terminal styling for beads CLI output.
+package ui
+
+import (
+	"os"
+
+	"github.com/charmbracelet/glamour"
+	"golang.org/x/term"
+)
+
+// RenderMarkdown renders markdown text using glamour with beads theme colors.
+// Returns the rendered markdown or the original text if rendering fails.
+// Word wraps at terminal width (or 80 columns if width can't be detected).
+func RenderMarkdown(markdown string) string {
+	// Skip glamour in agent mode to keep output clean for parsing
+	if IsAgentMode() {
+		return markdown
+	}
+
+	// Skip glamour if colors are disabled
+	if !ShouldUseColor() {
+		return markdown
+	}
+
+	// Detect terminal width for word wrap
+	// Cap at 100 chars for readability - wider lines cause eye-tracking fatigue
+	// Typography research suggests 50-75 chars optimal, 80-100 comfortable max
+	const maxReadableWidth = 100
+	wrapWidth := 80 // default if terminal size unavailable
+	if w, _, err := term.GetSize(int(os.Stdout.Fd())); err == nil && w > 0 {
+		wrapWidth = w
+	}
+	if wrapWidth > maxReadableWidth {
+		wrapWidth = maxReadableWidth
+	}
+
+	// Create renderer with auto-detected style (respects terminal light/dark mode)
+	renderer, err := glamour.NewTermRenderer(
+		glamour.WithAutoStyle(),
+		glamour.WithWordWrap(wrapWidth),
+	)
+	if err != nil {
+		// fallback to raw markdown on error
+		return markdown
+	}
+
+	rendered, err := renderer.Render(markdown)
+	if err != nil {
+		// fallback to raw markdown on error
+		return markdown
+	}
+
+	return rendered
+}