fix: add bytefield-svg for CTP generation (#989)

Processor CTP generation requires the package `bytefield-svg`.
Previously the following errors were encountered

```sh
$ ./do gen:proc_ctp_html[RVI20-32]
asciidoctor: ERROR: ext/riscv-isa-manual/src/images/bytefield/pmp-rv32.edn: line 2: Failed to generate image: Could not find the 'bytefield-svg' executable in PATH; add it to the PATH or specify its location using the 'bytefield-svg' document attribute
/workspaces/riscv-unified-db/.home/.gems/ruby/3.2.0/gems/asciidoctor-diagram-2.3.2/lib/asciidoctor-diagram/diagram_source.rb:144:in `find_command'
/workspaces/riscv-unified-db/.home/.gems/ruby/3.2.0/gems/asciidoctor-diagram-2.3.2/lib/asciidoctor-diagram/bytefield/converter.rb:18:in `convert'
/workspaces/riscv-unified-db/.home/.gems/ruby/3.2.0/gems/asciidoctor-diagram-2.3.2/lib/asciidoctor-diagram/diagram_processor.rb:196:in `create_image_block'
...
```

Now the CTP can be generated:

<img width="1902" height="912" alt="image"
src="https://github.com/user-attachments/assets/cbdd77c4-735f-40c7-a5de-6a933e7625d9"
/>

Author: cmd05

backends/portfolio/tasks.rake

@@ -99,6 +99,7 @@ def pf_adoc2pdf(adoc_file, target_pname)
     "-a pdf-theme=#{$root}/ext/docs-resources/themes/riscv-pdf.yml",
     "-a pdf-fontsdir=#{$root}/ext/docs-resources/fonts",
     "-a imagesdir=#{$root}/ext/docs-resources/images",
+    "-a bytefield-svg=#{$root}/node_modules/.bin/bytefield-svg",
     "-r asciidoctor-diagram",
     "-r idl_highlighter",
     "-o #{target_pname}",
@@ -134,6 +135,7 @@ def pf_adoc2html(adoc_file, target_pname)
     "-v",
     "-a toc",
     "-a imagesdir=#{$root}/ext/docs-resources/images",
+    "-a bytefield-svg=#{$root}/node_modules/.bin/bytefield-svg",
     "-r asciidoctor-diagram",
     "-r idl_highlighter",
     "-o #{target_pname}",

package-lock.json

@@ -10,6 +10,7 @@
     "@commitlint/config-conventional": "19.8.0",
     "asciidoctor-mathjax": "^0.0.5",
     "prettier": "3.4.2",
-    "wavedrom-cli": "^3.1.1"
+    "wavedrom-cli": "^3.1.1",
+    "bytefield-svg": "^1.8.0"
   }
 }