Move commit message conventions to contrib/claude

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

contrib/claude/commit.md

@@ -0,0 +1,28 @@
+# Commit Messages
+
+Follow the [seven rules of a great Git commit message](https://cbea.ms/git-commit/):
+
+1. Separate subject from body with a blank line
+2. Limit the subject line to 50 characters
+3. Capitalize the subject line
+4. Do not end the subject line with a period
+5. Use the imperative mood in the subject line
+6. Wrap the body at 72 characters
+7. Use the body to explain *what* and *why* vs. *how*
+
+The subject line should complete the sentence: "If applied, this commit will *your subject line here*".
+
+```
+Add vendor assessment agent for third-party reviews
+
+The existing changelog generator only covers internal changes.
+This introduces a dedicated agent that evaluates third-party
+vendors against our compliance criteria, producing a structured
+risk report.
+```
+
+Not every commit needs a body -- a single line is fine when the change is self-explanatory:
+
+```
+Fix typo in vendor assessment prompt
+```