[refactor] emit_mcp_error_response — tighten PID regex to disallow leading zeros

[kiki830621]

Problem

che-telegram-all-mcp-wrapper.sh:121 ^[0-9]+$ accepts 0123. JSON number with leading zeros violates RFC 8259 §6. jq lenient, but spec-conformant clients may reject.

Reachability: echo $$ never produces leading-zero PIDs; only manual file corruption.

Surfaced by Codex (P3 #5), Logic Reviewer (Finding 1 LOW).

Expected

Tighten regex:

if [[ "$owner_pid" =~ ^[1-9][0-9]*$ ]] && [ "$owner_pid" != "0" ]; then

Priority

P3 — unreachable from realistic input.

Source: surfaced during /idd-verify che-msg#31 (sister bug from verify ensemble — Codex + Devil's Advocate flagged convergently)

Verify report: #90 (comment)
Related issue: PsychQuant/che-msg#31
Related PR: psychquant-claude-plugins#90 (PR-1 ships v1.3.2)

🤖 Filed by /idd-verify Step 5b follow-up triage.