feat(v2): OpenCode agent provider

- Add OpenCodeProvider (SSE, session resume, MCP via mcp-to-opencode)
- Register opencode in factory; AGENT_PROVIDER passthrough from DB
- Host: XDG mount, NO_PROXY merge, OPENCODE_* env for opencode sessions
- Dockerfile: opencode-ai CLI; docs checklist + architecture diagram
- Skill add-opencode for v2; AgentProviderName in src/types.ts

Made-with: Cursor

container/agent-runner/src/providers/mcp-to-opencode.test.ts

@@ -0,0 +1,59 @@
+import { describe, it, expect } from 'bun:test';
+
+import { mcpServersToOpenCodeConfig } from './mcp-to-opencode.js';
+
+describe('mcpServersToOpenCodeConfig', () => {
+  it('maps nanoclaw + extra server like v2 index.ts merge', () => {
+    const servers = {
+      nanoclaw: {
+        command: 'node',
+        args: ['/app/src/mcp-tools/index.js'],
+        env: {
+          SESSION_INBOUND_DB_PATH: '/workspace/inbound.db',
+          SESSION_OUTBOUND_DB_PATH: '/workspace/outbound.db',
+          SESSION_HEARTBEAT_PATH: '/workspace/.heartbeat',
+        },
+      },
+      extra: {
+        command: 'npx',
+        args: ['-y', 'some-mcp'],
+        env: { FOO: 'bar' },
+      },
+    };
+
+    const mcp = mcpServersToOpenCodeConfig(servers);
+
+    expect(mcp.nanoclaw).toEqual({
+      type: 'local',
+      command: ['node', '/app/src/mcp-tools/index.js'],
+      environment: {
+        SESSION_INBOUND_DB_PATH: '/workspace/inbound.db',
+        SESSION_OUTBOUND_DB_PATH: '/workspace/outbound.db',
+        SESSION_HEARTBEAT_PATH: '/workspace/.heartbeat',
+      },
+      enabled: true,
+    });
+
+    expect(mcp.extra).toEqual({
+      type: 'local',
+      command: ['npx', '-y', 'some-mcp'],
+      environment: { FOO: 'bar' },
+      enabled: true,
+    });
+  });
+
+  it('omits environment when env is empty', () => {
+    const mcp = mcpServersToOpenCodeConfig({
+      x: { command: 'true', args: [], env: {} },
+    });
+    expect(mcp.x).toEqual({
+      type: 'local',
+      command: ['true'],
+      enabled: true,
+    });
+  });
+
+  it('returns empty record for undefined', () => {
+    expect(mcpServersToOpenCodeConfig(undefined)).toEqual({});
+  });
+});