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/web/src/hooks/useSessionStream.ts

@@ -123,6 +123,8 @@ function applyFrame(state: State, frame: WsFrame): State {
               ...(frame.tokens_used !== undefined ? { tokens_used: frame.tokens_used } : {}),
               ...(frame.ctx_used !== undefined ? { ctx_used: frame.ctx_used } : {}),
               ...(frame.ctx_max !== undefined ? { ctx_max: frame.ctx_max } : {}),
+              ...(frame.cache_tokens !== undefined ? { cache_tokens: frame.cache_tokens } : {}),
+              ...(frame.reasoning_tokens !== undefined ? { reasoning_tokens: frame.reasoning_tokens } : {}),
               ...(frame.started_at !== undefined ? { started_at: frame.started_at } : {}),
               ...(frame.finished_at !== undefined ? { finished_at: frame.finished_at } : {}),
               ...(frame.model !== undefined ? { model: frame.model } : {}),