fix(server): stamp resultType on the hand-written stateless tool results

[lnuxe]

Fixes #562.

Problem

test_logging_tool and test_streaming_elicitation are the two stateless
tools/call branches that write their response by hand: each emits a
notification line first, so it cannot use res.json(). Writing directly with
res.end(JSON.stringify(...)) also bypassed normalizeStatelessResponse, so
their results came back without resultType:

{ "jsonrpc": "2.0", "id": 1, "result": { "content": [ { "type": "text", "text": "Logging evaluated" } ] } }

resultType is a MUST on results on the 2026-07-28 wire, so the reference
fixture was failing the rule the suite grades, and the dedicated
test_logging_tool branch stayed outside the normalization that #462 applied to
the streamed tool responses.

Change

Both branches now build their payload and pass it through
normalizeStatelessResponse(method, ...) - the same helper the neighbouring
sendStatelessJson dispatch already uses. The notification frames are
untouched.

Evidence

New src/scenarios/server/draft-result-fields.test.ts, the server-direction
counterpart of src/scenarios/client/draft-result-fields.test.ts, before the
fixture fix:

FAIL  src/scenarios/server/draft-result-fields.test.ts > everything-server stateless tools/call results (2026-07-28) > test_logging_tool result carries the draft-required resultType
AssertionError: expected { content: [ { type: 'text', ...(1) } ] } to deeply equal { resultType: 'complete', ...(1) }
-   "resultType": "complete",

Both cases failed the same way; after the fix:

? src/scenarios/server/draft-result-fields.test.ts (2 tests) 1096ms

The test also pins the notification frame of each branch: tools/call with no
logLevel _meta must not log, and the elicitation branch writes its
notifications/progress line unconditionally.

Verification

• npm test - 49 files, 643 tests passed
• npm run lint (eslint + prettier --check .) - clean
• npm run typecheck - clean

I reproduced it against the fixture directly (npx tsx examples/servers/typescript/everything-server.ts, then POST tools/call with
MCP-Protocol-Version: 2026-07-28); no real-SDK run was needed because the
change is confined to the fixture's own response shape, which no check
inspects.

Per AGENTS.md this was prepared with an AI coding agent pointed at this open
issue as the concrete target; I reviewed every change and ran the commands
above myself.