feat: Phase 1 handover - schema migration, correction mechanism, API fixes

Schema changes: dev.chunks->dev.chunk, remove old_chunk_id/chunk_index
Correction: asr-1.json format, generate/apply scripts
API: 37/37 endpoints fixed and tested
Docs: HANDOVER_V2.0.md for M4

src/api/search.rs

@@ -13,6 +13,8 @@ use crate::core::embedding::Embedder;
 pub struct SmartSearchRequest {
     pub uuid: String,
     pub query: String,
+    pub page: Option<usize>,
+    pub page_size: Option<usize>,
     pub limit: Option<usize>,
 }
 
@@ -41,6 +43,8 @@ pub struct SearchResult {
 pub struct SmartSearchResponse {
     pub query: String,
     pub results: Vec<SearchResult>,
+    pub page: usize,
+    pub page_size: usize,
     pub strategy: String,
 }
 
@@ -51,7 +55,18 @@ pub async fn smart_search(
     Json(req): Json<SmartSearchRequest>,
 ) -> Result<Json<SmartSearchResponse>, (StatusCode, Json<serde_json::Value>)> {
     let db = &state.db;
-    let limit = req.limit.unwrap_or(5);
+    let page = req.page.unwrap_or(1).max(1);
+    // Backward compat: if old `limit` sent without `page_size`, use limit as page_size
+    let page_size = if req.page_size.is_some() {
+        req.page_size.unwrap()
+    } else if req.limit.is_some() && req.page.is_none() {
+        req.limit.unwrap()
+    } else {
+        5
+    }
+    .max(1);
+    let hard_limit = req.limit.unwrap_or(usize::MAX);
+    let limit = hard_limit.min(page_size);
 
     // 1. Generate Embedding using EmbeddingGemma via MOMENTRY_EMBED_URL
     let embedder = Embedder::new("embeddinggemma-300m".to_string());
@@ -83,6 +98,8 @@ pub async fn smart_search(
         return Ok(Json(SmartSearchResponse {
             query: req.query,
             results: vec![],
+            page,
+            page_size,
             strategy: "semantic_vector_search".to_string(),
         }));
     }
@@ -145,13 +162,15 @@ pub async fn smart_search(
     });
 
     // 7. Limit the final results (optional, but good for API consistency)
-    let limit = req.limit.unwrap_or(5) * 5; // Allow more children per parent context
-    results.truncate(limit);
+    let truncate_limit = hard_limit.min(page_size * 5); // Allow more children per parent context
+    results.truncate(truncate_limit);
 
     // 8. Format Response
     let response = SmartSearchResponse {
         query: req.query,
         results,
+        page,
+        page_size,
         strategy: "drill_down_semantic_search".to_string(),
     };