Fix serena MCP context to use engine-specific values instead of hardcoded "codex"

[Copilot]

Smoke test run 21112904973 failed on serena Go test with go: command not found. Root cause: serena MCP server was hardcoded to --context codex regardless of engine, causing wrong runtime environment.

Changes

Core fix:

• pkg/workflow/mcp-config-serena.go: Added engineID parameter to renderSerenaMCPConfigWithOptions(), uses engine-specific context with fallback to "codex"
• pkg/workflow/mcp_renderer.go: Added EngineID field to MCPRendererOptions, passes engine ID to serena renderer

Engine renderers:

• Updated claude_mcp.go, codex_mcp.go, copilot_mcp.go to pass e.id when creating renderer

Tests:

• Updated test calls to pass "codex" as engine ID parameter

Result

Workflows now use correct serena context:

• Copilot workflows → --context copilot
• Claude workflows → --context claude
• Codex workflows → --context codex

Note: GitHub MCP test failure in same run is unrelated (Copilot agent not providing required tool parameters - requires Copilot CLI team investigation).

Original prompt

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This section details on the original issue you should resolve

<issue_title>Smoke Test: Copilot - 21112904973</issue_title>
<issue_description># Smoke Test Results

Run ID: 21112904973
Timestamp: 2026-01-18T14:00:25.801Z
Status: ❌ FAIL

Test Results

Test	Status
GitHub MCP	❌ Tool parameter errors, gh CLI not authenticated
Serena Go	❌ go: command not found
Playwright	✅ Successfully navigated to GitHub
File Writing	✅ Test file created
Bash Tool	✅ File verified

Passed: 3/5

View Run

AI generated by Smoke Copilot for #10562

Comments on the Issue (you are @copilot in this section)

• Fixes Smoke Test: Copilot - 21112904973 #10576

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