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/inference/turn.ts

@@ -144,6 +144,7 @@ export async function runAssistantTurn(
           log: ctx.log,
           broker: ctx.broker,
           chatId,
+          hooks: ctx.hooks,
         });
       } catch (err) {
         ctx.log.warn({ err, chatId }, 'auto-compaction failed; clearing flag and proceeding');
@@ -214,6 +215,16 @@ export async function runAssistantTurn(
 
     // ---- non-tool finish → finalize and exit ----
     if (result.toolCalls.length === 0) {
+      // vWhale: Stop hook (best-effort, non-blocking).
+      if (ctx.hooks) {
+        ctx.hooks.run('Stop', {
+          event: 'Stop',
+          session_id: sessionId,
+          chat_id: chatId,
+          last_assistant_text: result.content.slice(0, 500),
+          turn: stepNumber,
+        }).catch(() => {});
+      }
       await finalizeCompletion(ctx, iterArgs, result, state.startedAt, iterSession);
       break;
     }
@@ -309,6 +320,22 @@ export async function runAssistantTurn(
     assistantMessageId = toolPhaseResult.nextAssistantId!;
   }
 
+  // vWhale: Stop hook at post-loop exit (best-effort, non-blocking).
+  if (ctx.hooks) {
+    const loaded = await loadContext(ctx.sql, sessionId, chatId);
+    const lastAssistant = loaded?.history?.slice().reverse().find(
+      (m: import('../../types/api.js').Message) => m.role === 'assistant',
+    );
+    const content = lastAssistant?.content ?? '';
+    ctx.hooks.run('Stop', {
+      event: 'Stop',
+      session_id: sessionId,
+      chat_id: chatId,
+      last_assistant_text: content.slice(0, 500),
+      turn: stepNumber,
+    }).catch(() => {});
+  }
+
   // ---- post-loop: step-cap sentinel ----
   // When the loop exits because stepNumber reached effectiveCap, the last
   // iteration's tool phase returned 'continue' with a nextAssistantId that