refactor: entries + secrets 双表，search 展示 field schema，key_ref PEM 共享

- secrets 表拆为 entries（主表）+ secrets（每字段一行）
- search 无需 master_key 即可展示 secrets 字段名、类型、长度
- inject/run 支持 metadata.key_ref 引用 kind=key 记录，PEM 轮换 O(1)
- entries_history + secrets_history 字段级历史，rollback 按 version 恢复
- 移除迁移用 DROP 语句，migrate 幂等
- v0.8.0

Made-with: Cursor

src/main.rs

@@ -186,9 +186,6 @@ EXAMPLES:
         /// Fuzzy keyword (matches name, namespace, kind, tags, metadata text)
         #[arg(short, long)]
         query: Option<String>,
-        /// Deprecated: search never reveals secrets; use inject/run instead
-        #[arg(long)]
-        show_secrets: bool,
         /// Extract metadata field value(s) directly: metadata.<key> (repeatable)
         #[arg(short = 'f', long = "field")]
         fields: Vec<String>,
@@ -528,7 +525,6 @@ async fn main() -> Result<()> {
             name,
             tag,
             query,
-            show_secrets,
             fields,
             summary,
             limit,
@@ -546,7 +542,6 @@ async fn main() -> Result<()> {
                     name: name.as_deref(),
                     tags: &tag,
                     query: query.as_deref(),
-                    show_secrets,
                     fields: &fields,
                     summary,
                     limit,