fix: shorten OpenCode temporary MCP tool names and keep them stable per conversation

Use gbd-/gbc- prefixes with a 6-char conversation hash instead of 20-char per-request hashes, lease per-conversation slots so parallel requests never share a name, and expose gateway custom tools as <server hash>_<name> within the 64-char provider limit.

src/main/agent/knowledge-mcp-gateway.ts

@@ -77,7 +77,7 @@ import type {
   ResolvedMcpServer
 } from '../capabilities/capability-service'
 import {
-  createMcpToolName,
+  createGatewayMcpToolName,
   isValidMcpToolName,
   listAllMcpTools,
   normalizeMcpToolSchema
@@ -848,7 +848,7 @@ export class KnowledgeMcpGateway {
             >(normalizeMcpToolSchema(tool.outputSchema))
           : undefined,
         exposedTool: {
-          name: createMcpToolName(server.id, tool.name),
+          name: createGatewayMcpToolName(server.id, tool.name),
           title: `${server.name} / ${tool.name}`.slice(0, 200),
           description: [
             `GoodBuddy 代理的自定义 MCP Server「${server.name}」工具。`,