docs: point the signature section at the current marks directory

Both paths it named were gone. The marks moved into ~/pictures/signature/ and gained an initials stamp the section never mentioned.

I described the stow source rather than naming a path, since a pinned path is what rotted it the first time. The directory's README carries the sizing guidance, so the section points there instead of restating it.

1 files changed, 18 insertions, 7 deletions

diff --git a/.ai/protocols.org b/.ai/protocols.org
index b291d9e..3e32074 100644
--- a/.ai/protocols.org
+++ b/.ai/protocols.org
@@ -307,15 +307,26 @@ gpg -d file.json.gpg > file.json       # decrypt (pinentry GUI handles passphras
 
 ** Signature Image
 
-A transparent-background PNG scan of Craig's handwritten signature lives at
-=~/pictures/cj-sig-transparent.png= (324×213, cropped), with a higher-resolution
-version at =~/pictures/cj-sig-no-background.png= (1536×1024). Both are symlinks
-into the archsetup stow dotfiles (=~/code/archsetup/dotfiles/common/pictures/=),
-so they're present on every machine. RGBA, transparent background; composites
-cleanly over a form line.
+Craig's handwritten marks live in =~/pictures/signature/=, all
+transparent-background PNGs that composite cleanly over a form line:
+
+| File                           | What it is                                     |
+|--------------------------------+------------------------------------------------|
+| =cj-signature-transparent.png= | Full signature, 324×213. The everyday one.     |
+|--------------------------------+------------------------------------------------|
+| =cj-signature-large.png=       | Same signature at 1536×1024, for print.        |
+|--------------------------------+------------------------------------------------|
+| =cj-initials-transparent.png=  | Handwritten CJ monogram, 65×66. Initial boxes. |
+|--------------------------------+------------------------------------------------|
+
+The directory is stow-managed from Craig's dotfiles repo, so it's present on
+every machine. Its =README.md= carries the ImageMagick pipeline the marks were
+keyed with, and the sizing guidance for placing one on a form — signature fields
+are usually thin baseline strips, so a mark fitted inside the strip shrinks to an
+illegible speck. Read it before stamping rather than guessing at a size.
 
 Default for signing documents is still Craig signing by hand in Xournal++. Only
-overlay this image onto a PDF (or other document) when Craig *explicitly asks
+overlay one of these onto a PDF (or other document) when Craig *explicitly asks
 for it on a specific document* — never sign for him on your own initiative. The
 =edit-pdf= workflow (project-level, where present) has the reportlab snippet for
 stamping it.