refactor(proxy): replace panic-prone unwrap/expect with safe patterns

Harden the proxy module against panics by removing optimistic
unwrap()/expect() calls in favor of pattern matching and graceful
fallbacks:

- copilot_optimizer/cache_injector: bind Value::Array/String directly
  instead of is_array()+as_array().unwrap(); use is_none_or and in-place
  string mutation
- hyper_client: gate the raw-write path with if-let + filter instead of
  has_cases + unwrap()
- gemini_shadow: recover poisoned RwLock via into_inner() rather than
  panicking, with warn logging
- streaming_codex_chat: replace expect("tool state exists") with
  let-else (return/continue)
- merge_tool_results: early-return when messages is absent
- sse: fall back to from_utf8_lossy on the UTF-8 boundary slice

No behavior change on the happy path; all proxy tests pass.

src-tauri/src/proxy/copilot_optimizer.rs

@@ -87,14 +87,13 @@ pub fn classify_request(
     // copilot-api 通过先 merge（text 吸收进 tool_result）再 classify 实现同等效果；
     // 直接在分类层处理更稳健，不依赖 merge 启用状态和执行顺序。
     let is_user_initiated = match last_msg.get("content") {
-        Some(content) if content.is_array() => {
-            let blocks = content.as_array().unwrap();
+        Some(Value::Array(blocks)) => {
             // 含有 tool_result → 工具续写（agent），否则 → 用户发起（user）
             !blocks
                 .iter()
                 .any(|block| block.get("type").and_then(|t| t.as_str()) == Some("tool_result"))
         }
-        Some(content) if content.is_string() => true,
+        Some(Value::String(_)) => true,
         _ => false,
     };
 
@@ -124,7 +123,9 @@ fn is_warmup_request(body: &Value, has_anthropic_beta: bool, is_compact: bool) -
         return false;
     }
     // 无工具定义
-    !matches!(body.get("tools"), Some(tools) if tools.is_array() && !tools.as_array().unwrap().is_empty())
+    body.get("tools")
+        .and_then(|tools| tools.as_array())
+        .is_none_or(|tools| tools.is_empty())
 }
 
 /// 检测是否为 Claude Code 上下文压缩/compact 请求。
@@ -228,7 +229,10 @@ pub fn merge_tool_results(mut body: Value) -> Value {
     }
 
     // Phase 2: 跨消息合并 — 连续的 tool_result-only 用户消息合并
-    let messages = body["messages"].as_array().unwrap().clone();
+    let messages = match body.get("messages").and_then(|m| m.as_array()) {
+        Some(messages) => messages.clone(),
+        None => return body,
+    };
     if messages.len() <= 1 {
         return body;
     }
@@ -422,10 +426,8 @@ pub fn sanitize_orphan_tool_results(mut body: Value) -> Value {
             // 空 tool_use_id 或不在紧邻 assistant 的 tool_use 中 → orphan
             if tool_use_id.is_empty() || !prev_tool_use_ids.contains(tool_use_id) {
                 let content_text = match block.get("content") {
-                    Some(c) if c.is_string() => c.as_str().unwrap_or("").to_string(),
-                    Some(c) if c.is_array() => c
-                        .as_array()
-                        .unwrap()
+                    Some(Value::String(text)) => text.clone(),
+                    Some(Value::Array(blocks)) => blocks
                         .iter()
                         .filter_map(|b| b.get("text").and_then(|t| t.as_str()))
                         .collect::<Vec<_>>()
@@ -483,10 +485,8 @@ pub fn strip_thinking_blocks(mut body: Value) -> Value {
 /// 从请求体的 `system` 字段提取文本（处理 string/array 两种格式）。
 fn extract_system_text(body: &Value) -> String {
     match body.get("system") {
-        Some(s) if s.is_string() => s.as_str().unwrap_or("").to_string(),
-        Some(arr) if arr.is_array() => arr
-            .as_array()
-            .unwrap()
+        Some(Value::String(text)) => text.clone(),
+        Some(Value::Array(blocks)) => blocks
             .iter()
             .filter_map(|b| b.get("text").and_then(|t| t.as_str()))
             .collect::<Vec<_>>()
@@ -573,13 +573,12 @@ fn append_text_to_tool_result(tool_result: &mut Value, text_block: &Value) {
     }
 
     // tool_result 的 content 可以是字符串或数组
-    match tool_result.get("content") {
-        Some(c) if c.is_string() => {
-            let existing = c.as_str().unwrap_or("");
-            tool_result["content"] = Value::String(format!("{existing}\n{text}"));
+    match tool_result.get_mut("content") {
+        Some(Value::String(existing)) => {
+            existing.push('\n');
+            existing.push_str(text);
         }
-        Some(c) if c.is_array() => {
-            let arr = tool_result["content"].as_array_mut().unwrap();
+        Some(Value::Array(arr)) => {
             arr.push(serde_json::json!({"type": "text", "text": text}));
         }
         _ => {
@@ -592,21 +591,18 @@ fn append_text_to_tool_result(tool_result: &mut Value, text_block: &Value) {
 /// 从消息中提取文本内容
 fn extract_text_from_message(msg: &Value) -> String {
     match msg.get("content") {
-        Some(content) if content.is_string() => content.as_str().unwrap_or("").to_string(),
-        Some(content) if content.is_array() => {
-            let blocks = content.as_array().unwrap();
-            blocks
-                .iter()
-                .filter_map(|block| {
-                    if block.get("type").and_then(|t| t.as_str()) == Some("text") {
-                        block.get("text").and_then(|t| t.as_str())
-                    } else {
-                        None
-                    }
-                })
-                .collect::<Vec<_>>()
-                .join(" ")
-        }
+        Some(Value::String(text)) => text.clone(),
+        Some(Value::Array(blocks)) => blocks
+            .iter()
+            .filter_map(|block| {
+                if block.get("type").and_then(|t| t.as_str()) == Some("text") {
+                    block.get("text").and_then(|t| t.as_str())
+                } else {
+                    None
+                }
+            })
+            .collect::<Vec<_>>()
+            .join(" "),
         _ => String::new(),
     }
 }