fix: 修复 SmartSearch 的 ripgrep limit 和 FTS 分词器问题

- Ripgrep 模式: 添加总结果数量限制，防止返回超过 2MB 数据
  - --max-count 只限制每个文件的匹配数，现在在收集结果时应用 limit
  - 达到限制时在 metadata 中添加 warning 提示

- FTS 分词器: 将点号(.)添加到 tokenchars，修复 PortRole.FLOW 等带点号标识符的精确搜索
  - 更新 dir_index.py 和 migration_004_dual_fts.py 中的 tokenize 配置
  - 需要重建索引才能生效

- Exact 模式: 添加 fuzzy 回退，当精确搜索无结果时自动尝试模糊搜索
  - 回退时在 metadata 中标注 fallback: 'fuzzy'

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

codex-lens/src/codexlens/storage/dir_index.py

@@ -1651,16 +1651,17 @@ class DirIndexStore:
             from codexlens.storage.sqlite_utils import check_trigram_support
 
             has_trigram = check_trigram_support(conn)
-            fuzzy_tokenizer = "trigram" if has_trigram else "unicode61 tokenchars '_-'"
+            fuzzy_tokenizer = "trigram" if has_trigram else "unicode61 tokenchars '_-.'"
 
             # Exact FTS table with unicode61 tokenizer
+            # Note: tokenchars includes '.' to properly tokenize qualified names like PortRole.FLOW
             conn.execute(
                 """
                 CREATE VIRTUAL TABLE IF NOT EXISTS files_fts_exact USING fts5(
                     name, full_path UNINDEXED, content,
                     content='files',
                     content_rowid='id',
-                    tokenize="unicode61 tokenchars '_-'"
+                    tokenize="unicode61 tokenchars '_-.'"
                 )
                 """
             )

codex-lens/src/codexlens/storage/migrations/migration_004_dual_fts.py

@@ -45,7 +45,7 @@ def upgrade(db_conn: Connection):
                 f"Trigram tokenizer not available (requires SQLite >= 3.34), "
                 f"using extended unicode61 tokenizer for fuzzy matching"
             )
-            fuzzy_tokenizer = "unicode61 tokenchars '_-'"
+            fuzzy_tokenizer = "unicode61 tokenchars '_-.'"
 
         # Start transaction
         cursor.execute("BEGIN TRANSACTION")
@@ -122,7 +122,8 @@ def upgrade(db_conn: Connection):
         # Drop old FTS table
         cursor.execute("DROP TABLE IF EXISTS files_fts")
 
-        # Create exact FTS table (unicode61 with underscores/hyphens as token chars)
+        # Create exact FTS table (unicode61 with underscores/hyphens/dots as token chars)
+        # Note: tokenchars includes '.' to properly tokenize qualified names like PortRole.FLOW
         log.info("Creating files_fts_exact table with unicode61 tokenizer...")
         cursor.execute(
             """
@@ -130,7 +131,7 @@ def upgrade(db_conn: Connection):
                 name, full_path UNINDEXED, content,
                 content='files',
                 content_rowid='id',
-                tokenize="unicode61 tokenchars '_-'"
+                tokenize="unicode61 tokenchars '_-.'"
             )
             """
         )