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/message-columns.ts

@@ -7,10 +7,12 @@
 
 export const MESSAGE_COLUMNS =
   'id, session_id, chat_id, role, content, kind, tool_calls, tool_results, status, last_seq, ' +
-  'tokens_used, ctx_used, ctx_max, started_at, finished_at, created_at, metadata, ' +
+  'tokens_used, ctx_used, ctx_max, cache_tokens, reasoning_tokens, ' +
+  'started_at, finished_at, created_at, metadata, ' +
   'summary, tail_start_id, compacted_at, model';
 
 export const INFERENCE_MESSAGE_COLUMNS =
   'id, session_id, chat_id, role, content, kind, tool_calls, tool_results, status, last_seq, ' +
-  'tokens_used, ctx_used, ctx_max, started_at, finished_at, created_at, metadata, ' +
+  'tokens_used, ctx_used, ctx_max, cache_tokens, reasoning_tokens, ' +
+  'started_at, finished_at, created_at, metadata, ' +
   'reasoning_parts, model';