feat(deepseek): switch presets to V4 (flash/pro) and add pricing

DeepSeek released V4 flash/pro; legacy IDs deepseek-chat / deepseek-reasoner
now alias to deepseek-v4-flash and will be deprecated.

- Update claude/hermes/opencode/openclaw presets to v4-pro / v4-flash,
  context 128K -> 1M; Claude Anthropic-compat endpoint routes OPUS/SONNET
  to v4-pro and HAIKU to v4-flash, plus an explicit modelsUrl override.
- Seed deepseek-v4-flash ($0.14/$0.28 per 1M) and deepseek-v4-pro
  ($1.68/$3.36 per 1M) into model_pricing; older v3.x / chat / reasoner
  rows kept for historical usage stats (INSERT OR IGNORE).
- Refresh user-manual (zh/en/ja) pricing table and note that legacy model
  IDs are billed at v4-flash rates.

src/config/opencodeProviderPresets.ts

@@ -338,8 +338,8 @@ export const opencodeProviderPresets: OpenCodeProviderPreset[] = [
         setCacheKey: true,
       },
       models: {
-        "deepseek-chat": { name: "DeepSeek V3.2" },
-        "deepseek-reasoner": { name: "DeepSeek R1" },
+        "deepseek-v4-pro": { name: "DeepSeek V4 Pro" },
+        "deepseek-v4-flash": { name: "DeepSeek V4 Flash" },
       },
     },
     category: "cn_official",