fix: build_config.py 幂等化，消除每次运行累加空白行

- 添加空白行折叠（≥4空行→2空行），确保多次运行输出一致
- 修复 regex 模式匹配

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

Author: Pigbibi

scripts/build_config.py

@@ -179,7 +179,7 @@ def inject_into_index_html(config: dict) -> None:
     # Generate platform JS
     js_block = build_platform_meta_js(config)
 
-    # Remove ALL old hardcoded platform blocks (count=0 = replace all)
+    # Remove ALL old hardcoded platform blocks (count=0 = replace all).
     for pattern in [
         r"    const defaultRepositories = \{[\s\S]*?\n    \};\n(?:\s*// Alias for backward compatibility\n\s*const defaultRepositories = platformRepositories;\n)?",
         r"    const platformRepositories = \{[\s\S]*?\n    \};\n(?:\s*// Alias for backward compatibility\n\s*const defaultRepositories = platformRepositories;\n)?",
@@ -190,6 +190,9 @@ def inject_into_index_html(config: dict) -> None:
     ]:
         html = re.sub(pattern, "", html, count=0)
 
+    # Collapse runs of 3+ blank lines to 2 so builds are idempotent.
+    html = re.sub(r"\n{4,}", "\n\n\n", html)
+
     # Insert generated JS: right after the <script> tag opening
     script_marker = "\n  <script>\n"
     insert_pos = html.find(script_marker)

web/strategy-switch-console/index.html

@@ -1612,48 +1612,6 @@ <h2 data-i18n="summary">切换摘要</h2>
     };
 
 
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     const reservePolicyModes = ["current", "none", "ratio", "floor", "max"];
     const incomeLayerModes = ["current", "enabled", "disabled"];
     const optionOverlayModes = ["current", "enabled", "disabled"];