Add PR validation before creating PRs

- Create validate-pr.sh: runs shellcheck, JSON/YAML/Python syntax checks
- Update gitea-pr.sh: runs validation before creating PR
- Update CLAUDE.md: document PR review policy
  - ~/.claude repo: linting/validation only
  - Code repos: full code-reviewer agent review

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

automation/validate-pr.sh

@@ -0,0 +1,82 @@
+#!/bin/bash
+# Validate changed files before PR creation
+# Runs: shellcheck, JSON validation, Python syntax check
+
+set -euo pipefail
+
+ERRORS=0
+
+# Get changed files compared to main
+CHANGED_FILES=$(git diff --name-only origin/main 2>/dev/null || git diff --name-only HEAD~1)
+
+echo "Validating changed files..."
+
+for file in $CHANGED_FILES; do
+    [[ -f "$file" ]] || continue
+
+    case "$file" in
+        *.sh)
+            if command -v shellcheck &>/dev/null; then
+                if ! shellcheck -S warning "$file" 2>/dev/null; then
+                    echo "FAIL: shellcheck $file"
+                    ((ERRORS++))
+                else
+                    echo "OK: $file"
+                fi
+            else
+                echo "SKIP: shellcheck not installed"
+            fi
+            ;;
+        *.json)
+            if ! python3 -m json.tool "$file" >/dev/null 2>&1; then
+                echo "FAIL: invalid JSON $file"
+                ((ERRORS++))
+            else
+                echo "OK: $file"
+            fi
+            ;;
+        *.yaml|*.yml)
+            if command -v yamllint &>/dev/null; then
+                if ! yamllint -d relaxed "$file" 2>/dev/null; then
+                    echo "FAIL: yamllint $file"
+                    ((ERRORS++))
+                else
+                    echo "OK: $file"
+                fi
+            elif python3 -c "import yaml" 2>/dev/null; then
+                if ! python3 -c "import yaml; yaml.safe_load(open('$file'))" 2>/dev/null; then
+                    echo "FAIL: invalid YAML $file"
+                    ((ERRORS++))
+                else
+                    echo "OK: $file"
+                fi
+            else
+                echo "SKIP: no YAML validator"
+            fi
+            ;;
+        *.py)
+            if ! python3 -m py_compile "$file" 2>/dev/null; then
+                echo "FAIL: Python syntax $file"
+                ((ERRORS++))
+            else
+                echo "OK: $file"
+            fi
+            ;;
+        *.md)
+            echo "OK: $file (markdown, no validation)"
+            ;;
+        *)
+            echo "SKIP: $file (no validator)"
+            ;;
+    esac
+done
+
+if [[ $ERRORS -gt 0 ]]; then
+    echo ""
+    echo "Validation failed with $ERRORS error(s)"
+    exit 1
+fi
+
+echo ""
+echo "All validations passed"
+exit 0