ci: make the Claude review lenses more thorough

At high effort, Opus 5.5 uses about half as many thinking tokens per review as
Opus 5 did. The lenses return after about five of their twenty minutes. Use
xhigh effort, and tell the lenses to go through every hunk of the diff instead
of stopping at the first findings.

.github/workflows/claude-review.yml

@@ -423,7 +423,7 @@ jobs:
           You have ${minutes} minutes. After that, tool calls are denied and you must return what you have."
             (cd "$dir" && REVIEW_DEADLINE=$(( $(date +%s) + minutes * 60 )) timeout --kill-after=30 "$((minutes + grace_minutes))m" claude \
               --model us.anthropic.claude-opus-5-5 \
-              --effort high \
+              --effort xhigh \
               --max-turns 100 \
               --setting-sources user \
               --tools Bash,Read,Grep,Glob \
@@ -495,9 +495,10 @@ jobs:
           "${context}
 
           Review the pull request through one lens only, ${name}: ${lenses[$name]}. Report only
-          findings you verified against diff.patch and the code. Only these severities are allowed
-          in this review round: ${ALLOWED_SEVERITIES}. Skip anything an existing review comment
-          already covers. ${previous}
+          findings you verified against diff.patch and the code. Do not stop after the first
+          findings. Go through every hunk of the diff you are reviewing, and report as many
+          verified issues as you can find. Only these severities are allowed in this review round:
+          ${ALLOWED_SEVERITIES}. Skip anything an existing review comment already covers. ${previous}
 
           A body states the problem and, when obvious, the fix, in one or two sentences of at most
           300 characters, without headings, lists, or restating the code. A suggestion block that