Prefix unused images with _ and restore TikZ figures from main

- Rename 409 unused image files with _ prefix across vol1 (272) and
  vol2 (137) so they are visually identifiable without being deleted
- Restore polished TikZ figures from main branch into vol2 chapters:
  fault_tolerance, edge_intelligence, security_privacy, distributed_training,
  responsible_ai, sustainable_ai, robust_ai
- Remove all tikz-source backup blocks (0 remaining across vol2)
- Prefix 33 SVG files superseded by restored TikZ with _
- Add GreenL0, chains, shapes.arrows, decorations.pathreplacing to diagram.yml

book/quarto/config/shared/base/diagram.yml

@@ -14,7 +14,7 @@ diagram:
         - '\usepackage{amssymb}'
         - '\usepackage{pifont}'
         - '\usepackage{xcolor}'
-        - '\pgfplotsset{compat=1.9}'
+        - '\pgfplotsset{compat=1.18}'
         - '\usepgfplotslibrary{fillbetween}'
         - '\usetikzlibrary{angles}'
         - '\usetikzlibrary{arrows.meta}'
@@ -22,15 +22,18 @@ diagram:
         - '\usetikzlibrary{backgrounds}'
         - '\usetikzlibrary{bending}'
         - '\usetikzlibrary{calc}'
+        - '\usetikzlibrary{chains}'
         - '\usetikzlibrary{shadows.blur}'
         - '\usetikzlibrary{fit}'
         - '\usetikzlibrary{intersections}'
         - '\usetikzlibrary{positioning}'
+        - '\usetikzlibrary{shapes.arrows}'
         - '\usetikzlibrary{shapes.geometric}'
         - '\usetikzlibrary{shapes}'
         - '\usetikzlibrary{quotes}'
         - '\usetikzlibrary{decorations.pathmorphing}'
         - '\usetikzlibrary{decorations.markings}'
+        - '\usetikzlibrary{decorations.pathreplacing}'
         - '\usetikzlibrary{matrix}'
         - '\usetikzlibrary{patterns}'
         - '\usepgfplotslibrary{dateplot}'
@@ -49,6 +52,7 @@ diagram:
         - '\definecolor{GreenL}{RGB}{219,253,166}'
         - '\definecolor{GreenLine}{HTML}{008F45}'
         - '\definecolor{GreenFill}{HTML}{D5F5E3}'
+        - '\definecolor{GreenL0}{HTML}{D5F5E3}'
         - '\definecolor{GrayLine}{HTML}{666666}'
         - '\definecolor{GrayL}{HTML}{E0E0E0}'
         - '\definecolor{Black}{HTML}{000000}'