patch: give the Claude workflow full git history

Check out with fetch-depth: 0 instead of 1. The agent is frequently asked
whether a ticket is already done, which needs git log / git blame; with a
depth-1 checkout it has neither and infers history from HEAD instead. On
stellar-dbt#1101 that produced a correct conclusion supported by a
fabricated commit attribution.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: chowbao

.github/workflows/claude.yml

@@ -82,7 +82,16 @@ jobs:
         with:
           repository: ${{ steps.checkout-target.outputs.repository || github.repository }}
           ref: ${{ steps.checkout-target.outputs.ref || github.ref }}
-          fetch-depth: 1
+          # Full history. The agent routinely has to decide whether a ticket is
+          # already done, and a depth-1 checkout leaves it with no `git log`,
+          # `git blame` or `git log -S` to answer that with. It then infers
+          # history from HEAD and gets it wrong: on stellar-dbt#1101 it
+          # correctly found the models already present, but attributed them to
+          # the commit at HEAD -- which touched only this workflow file --
+          # implying a repo-hygiene problem that did not exist. A wrong
+          # justification for a right answer is harder to catch than a wrong
+          # answer, so pay the clone cost and give it real history.
+          fetch-depth: 0
 
       - name: Exchange GitHub OIDC token for Anthropic access token
         id: anthropic-auth