fix: 7 项 E2E Bug 修复 — Dashboard 404 / 记忆去重 / 记忆注入 / invoice_id / Prompt 版本

P0:
- BUG-H1: Dashboard 路由 /api/v1/stats/dashboard → /api/v1/admin/dashboard

P1:
- BUG-H2: viking_add 预检查 content_hash 去重，返回 "deduped" 状态；SqliteStorage 启动时回填已有条目 content_hash
- BUG-M5: saas-relay-client 发送前调用 viking_inject_prompt 注入跨会话记忆

P2:
- BUG-M1: PaymentResult 添加 invoice_id 字段，query_payment_status 返回 invoice_id
- BUG-M2: UpdatePromptRequest 添加内容字段，更新时自动创建新版本并递增 current_version
- BUG-M3: viking_find scope 参数文档化（设计行为，调用方需传 agent scope）
- BUG-M4: Dashboard 路由缺失已修复，handler 层 require_admin 已正确返回 403

P3 (确认已修复/非代码问题):
- BUG-L1: pain_seed_categories 已统一，无 pain_seeds 残留
- BUG-L2: pipeline_create 参数格式正确，E2E 测试方法问题

crates/zclaw-growth/src/storage/sqlite.rs

@@ -179,6 +179,36 @@ impl SqliteStorage {
             .execute(&self.pool)
             .await;
 
+        // Backfill content_hash for existing entries that have NULL content_hash
+        {
+            use std::hash::{Hash, Hasher};
+
+            let rows: Vec<(String, String)> = sqlx::query_as(
+                "SELECT uri, content FROM memories WHERE content_hash IS NULL"
+            )
+            .fetch_all(&self.pool)
+            .await
+            .unwrap_or_default();
+
+            if !rows.is_empty() {
+                for (uri, content) in &rows {
+                    let normalized = content.trim().to_lowercase();
+                    let mut hasher = std::collections::hash_map::DefaultHasher::new();
+                    normalized.hash(&mut hasher);
+                    let hash = format!("{:016x}", hasher.finish());
+                    let _ = sqlx::query("UPDATE memories SET content_hash = ? WHERE uri = ?")
+                        .bind(&hash)
+                        .bind(uri)
+                        .execute(&self.pool)
+                        .await;
+                }
+                tracing::info!(
+                    "[SqliteStorage] Backfilled content_hash for {} existing entries",
+                    rows.len()
+                );
+            }
+        }
+
         // Create metadata table
         sqlx::query(
             r#"