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

packages/contracts/src/ws-frames.ts

@@ -116,6 +116,8 @@ export const MessageCompleteFrame = z.object({
   tokens_used: z.number().int().nonnegative().nullable().optional(),
   ctx_used: z.number().int().nonnegative().nullable().optional(),
   ctx_max: z.number().int().positive().nullable().optional(),
+  cache_tokens: z.number().int().nonnegative().nullable().optional(),
+  reasoning_tokens: z.number().int().nonnegative().nullable().optional(),
   started_at: IsoTimestamp.nullable().optional(),
   finished_at: IsoTimestamp.nullable().optional(),
   // nullable: external-coder turns carry task.model, which is null when no