docs(skill): note macOS NFD-filename gotcha for dscp/scp

Accented filenames on a macOS host are stored decomposed (NFD), so a precomposed
(NFC) remote path in scp/dscp silently fails with 'No such file or directory'.
Document the wildcard / list-first workaround in the pi-devbox-environment skill,
next to the dssh/dscp alias table. (Hit while copying a screenshot named
'Skärmavbild ….png' from the host.)

rootfs/usr/local/share/pi-devbox/skills/pi-devbox-environment/SKILL.md

@@ -91,6 +91,22 @@ are "command not found" there — you must spell out the underlying command.
 If a command "works in my terminal but not when the agent runs it," this alias
 gap is the first thing to suspect.
 
+**`dscp`/`scp` with accented filenames on a macOS host.** macOS stores filenames
+in Unicode **NFD** (decomposed — e.g. `ä` is `a` + combining U+0308), while the
+string you type or paste is usually **NFC** (precomposed `ä`, U+00E4). The bytes
+differ, so a precomposed remote path *silently* fails to match on the host —
+`scp … "mac:'~/Desktop/Skärmavbild ….png'"` returns *No such file or directory*
+even though the file plainly exists. Sidestep the encoding entirely: let the
+**remote shell expand a wildcard**, or list the directory first and copy the
+exact name it prints.
+
+```sh
+# glob dodges the NFC/NFD mismatch (the remote shell matches the real bytes):
+scp -F "$HOME/.ssh-local/config" "mac:~/Desktop/Sk*rmavbild*.png" ./
+# or read the exact filename first, then copy that:
+ssh -F "$HOME/.ssh-local/config" mac 'ls -1 ~/Desktop/*.png'
+```
+
 ## 3. Reaching the Docker host and its LAN over SSH
 
 When the host is VM-backed (e.g. OrbStack / Docker Desktop on macOS) the