Remove .claude/ from the repo, keep it ignored

Origo's own pitch is that its trustworthiness rests on being small enough
to read in full, and .claude/skills/audit/SKILL.md - an audit runbook
for driving an AI coding assistant - has nothing to do with the firmware
or its verification chain. Visible in a public repo for a seed tool, it
invites a question with nothing behind it: whether the code was written
and reviewed by a human or mostly by the tool that runbook drives. The
answer doesn't change by removing the file, but the question shouldn't
be there to ask.

Nothing here depended on it being tracked - the skill still works locally
without being versioned. Added to .gitignore alongside jade/, the
untracked Blockstream Jade reference copy that a broad `git add -A` has
already come close to sweeping into a commit once this session.

Verified with the host self-test and the 52 Python tests. No firmware
or code change.

Author: oroderico

.claude/skills/audit/SKILL.md

@@ -4,3 +4,9 @@ sdkconfig.old
 __pycache__/
 *.py[cod]
 
+# Local tooling and reference material, not part of the firmware or its
+# audit chain - kept off the repo so the tree stays the size the README
+# claims it is.
+.claude/
+jade/
+