feat: DeepSeek API integration + Whale lift (hooks, tool repair, MCP permissions, token tracking)

DeepSeek API:
- @ai-sdk/deepseek provider replaces openai-compatible for deepseek-* models
- Token tracking: cache_hit/reasoning tokens flow API → DB → WS frames → UI
- thinking effort levels (off/low/medium/high/xhigh/max) via AGENTS.md frontmatter
- V4 models: deepseek-v4-flash, deepseek-v4-pro
- Wired for both chat and coder panes

Whale lifts:
- Tool input repair (schema-based type coercion, markdown link unwrapping)
- Hooks system (6 lifecycle events, shell exec, JSON stdin/stdout contract)
- Per-MCP-server permissions (allow/ask/deny)
- token tracking UI (cache N, think N in message stats line)

Infra:
- New DB columns: messages.cache_tokens, messages.reasoning_tokens
- New WS frame fields: cache_tokens, reasoning_tokens on message_complete
- coder provider snapshot merges DeepSeek models alongside llama-swap

apps/server/src/services/agents.ts

@@ -106,6 +106,8 @@ interface ParsedFrontmatter {
   // allowed" — the model responds text-only.
   steps?: number;
   llama_extra_args?: string[];
+  // vDeepSeek: thinking effort for DeepSeek V4 models.
+  reasoning_effort?: string;
 }
 
 // P5: table-driven validation for the "soft-range" numeric frontmatter fields.
@@ -386,6 +388,7 @@ function parseAgentSection(section: RawSection): Omit<Agent, 'source'> {
     max_tool_calls: typeof fm.max_tool_calls === 'number' ? fm.max_tool_calls : null,
     steps: typeof fm.steps === 'number' ? fm.steps : null,
     llama_extra_args: Array.isArray(fm.llama_extra_args) ? fm.llama_extra_args : null,
+    reasoning_effort: typeof fm.reasoning_effort === 'string' ? (fm.reasoning_effort as Agent['reasoning_effort']) : null,
   };
 }