feat(search): SEARXNG_BASE_URL env-var fallback and expand wiki chunk column

- docker-compose.yml: pass SEARXNG_BASE_URL into mateclaw-server so the
  app can reach the searxng sidecar container out of the box (default
  http://searxng:8080).
- SystemSettingService: resolveSearxngBaseUrl() now falls back to the
  SEARXNG_BASE_URL env var when no DB value is set, so Docker users no
  longer need to configure it manually in the UI.
- V38 migration (h2 + mysql): expand mate_wiki_chunk.content from TEXT
  (64KB) to MEDIUMTEXT (16MB) so large Chinese chunks (~30k chars
  ≈ 90KB UTF-8) no longer overflow.

docker-compose.yml

@@ -71,6 +71,8 @@ services:
       SERPER_API_KEY: ${SERPER_API_KEY:-}
       JWT_SECRET: ${JWT_SECRET:-}
       MATECLAW_CORS_ALLOWED_ORIGINS: ${MATECLAW_CORS_ALLOWED_ORIGINS:-}
+      # SearXNG: tell the app where to reach the sidecar container
+      SEARXNG_BASE_URL: ${SEARXNG_BASE_URL:-http://searxng:8080}
     ports:
       - "18080:18088"   # host:container — app listens on 18088 inside the container
     volumes:

mateclaw-server/src/main/java/vip/mate/system/service/SystemSettingService.java

@@ -64,6 +64,18 @@ public class SystemSettingService {
 
     private final SystemSettingMapper systemSettingMapper;
 
+    /**
+     * Resolve the SearXNG base URL: DB value takes priority; fall back to the
+     * {@code SEARXNG_BASE_URL} environment variable so Docker deployments work
+     * out-of-the-box without manual configuration in the UI.
+     */
+    private String resolveSearxngBaseUrl() {
+        String dbValue = getValue(SEARXNG_BASE_URL_KEY, "");
+        if (dbValue != null && !dbValue.isBlank()) return dbValue;
+        String envValue = System.getenv("SEARXNG_BASE_URL");
+        return (envValue != null && !envValue.isBlank()) ? envValue : "";
+    }
+
     public SystemSettingsDTO getSettings() {
         SystemSettingsDTO dto = new SystemSettingsDTO();
         dto.setLanguage(getValue(LANGUAGE_KEY, "zh-CN"));
@@ -79,7 +91,7 @@ public class SystemSettingService {
         dto.setTavilyBaseUrl(getValue(TAVILY_BASE_URL_KEY, "https://api.tavily.com/search"));
         // Keyless provider 配置
         dto.setDuckduckgoEnabled(Boolean.parseBoolean(getValue(DUCKDUCKGO_ENABLED_KEY, "true")));
-        dto.setSearxngBaseUrl(getValue(SEARXNG_BASE_URL_KEY, ""));
+        dto.setSearxngBaseUrl(resolveSearxngBaseUrl());
         // API Key 脱敏回显
         dto.setSerperApiKeyMasked(maskApiKey(getValue(SERPER_API_KEY_KEY, "")));
         dto.setTavilyApiKeyMasked(maskApiKey(getValue(TAVILY_API_KEY_KEY, "")));
@@ -153,7 +165,7 @@ public class SystemSettingService {
         dto.setTavilyApiKey(getValue(TAVILY_API_KEY_KEY, ""));
         dto.setTavilyBaseUrl(getValue(TAVILY_BASE_URL_KEY, "https://api.tavily.com/search"));
         dto.setDuckduckgoEnabled(Boolean.parseBoolean(getValue(DUCKDUCKGO_ENABLED_KEY, "true")));
-        dto.setSearxngBaseUrl(getValue(SEARXNG_BASE_URL_KEY, ""));
+        dto.setSearxngBaseUrl(resolveSearxngBaseUrl());
         return dto;
     }
 

mateclaw-server/src/main/resources/db/migration/h2/V38__wiki_chunk_content_mediumtext.sql

@@ -0,0 +1,3 @@
+-- V38: Expand mate_wiki_chunk.content to CLOB (H2 equivalent of MEDIUMTEXT)
+-- H2's TEXT is already effectively unbounded, but align with MySQL change for consistency.
+ALTER TABLE mate_wiki_chunk ALTER COLUMN content CLOB NOT NULL;

mateclaw-server/src/main/resources/db/migration/mysql/V38__wiki_chunk_content_mediumtext.sql

@@ -0,0 +1,11 @@
+-- V38: Expand mate_wiki_chunk.content from TEXT (64KB) to MEDIUMTEXT (16MB)
+-- TEXT max = 65,535 bytes; a 30,000-char Chinese chunk needs ~90,000 bytes (3 bytes/char UTF-8).
+-- MEDIUMTEXT supports up to 16,777,215 bytes, safely covering any realistic chunk size.
+SET @c := (SELECT DATA_TYPE FROM INFORMATION_SCHEMA.COLUMNS
+           WHERE TABLE_SCHEMA = DATABASE()
+             AND TABLE_NAME   = 'mate_wiki_chunk'
+             AND COLUMN_NAME  = 'content');
+SET @s := IF(@c = 'text',
+             'ALTER TABLE mate_wiki_chunk MODIFY COLUMN content MEDIUMTEXT NOT NULL',
+             'SELECT 1');
+PREPARE stmt FROM @s; EXECUTE stmt; DEALLOCATE PREPARE stmt;