fix(mcp): keep startup diagnostics out of JSON-RPC stdout

[tom-sapletta-com]

Ticket: ticket-094
Correlation ID: koru-ticket-094-mcp-stdout

Starting the real MCP server emitted a human-readable activity banner on stdout, causing a JSON-RPC parse error in the client. The MCP entry point now selects the existing stderr activity format explicitly. Tool schemas and protocol responses remain unchanged.

Validation: real subprocess regression fails before the fix and passes after it; 14 focused MCP and quality tests pass (16 deselected by repository configuration), along with Ruff, managed governance and Docker Compose.

[ifuri-validator-agent]

Deterministic Validator approval for exact head 3d49b3cfff2e547d4b35ea2444104b3385024406.

Ticket: ticket-094
Correlation ID: koru-pr-130-ticket-094
Model: zai/glm-5.3
Reviewed diff chunks: 1
Advisory LLM verdict: APPROVE
Advisory summary: Reviewed all 1 diff chunk(s). Single-line fix routes the MCP startup activity diagnostic to the stderr format option so stdout remains pure JSON-RPC. A real-subprocess regression test parses every stdout line as JSON-RPC and asserts the banner lands on stderr. Scope matches intent. allowed paths; no interface, dependency, or workflow changes.
Advisory findings: none
The LLM output above is advisory and was not used as the approval trust root.

Actual PR impact radar

Exact range: 262b28fc7adf54f286d145e1e548ae3a60b27001...3d49b3cfff2e547d4b35ea2444104b3385024406
Change digest: 46c866dd2d2f951c01a50707ce0d4f065776143b2f4b83f388af95416b3bca82
Score: 52/100 (L), estimated 63 min, split recommended: true
Affected services/components: repository-wide/unclassified

Machine-readable radar JSONL and SVG

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Merge will be attempted after this approval when explicitly authorized. ## Decision record (recomputable)

DECISION D-094-9745
TICKET ticket-094
HEAD_SHA 3d49b3cfff2e547d4b35ea2444104b3385024406
CORRELATION_ID koru-pr-130-ticket-094
ACTOR agent:ifuri-validator-agent[bot]
APPLIED_RULE P-CORE-015
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INPUT required_checks_source = "protected registry + GitHub applied rules (env/request)"
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VERDICT APPROVE AUTHORITY DETERMINISTIC
REJECTED REQUEST_CHANGES BECAUSE NO_UNSAFE_CHANGE_REASON_FOUND
ADVISORY llm_verdict = "APPROVE" MODEL "zai/glm-5.3"
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