Add neuron-dev-setup: one-command CORE dev stack onboarding installer

Scaffolds a reproducible, idempotent installer that stands up the four native
launchd core services (soul :7770, engram :8742, mcp-wrapper :17779,
mcp-proxy :7779), seeds a fresh engram with the genesis identity via forge, and
installs the Claude Code config (neuron agent + core hooks + local MCP). Fully
templated to the invoking user's $HOME; Anthropic key prompted and stored in
Keychain; no secrets committed. Personal automations and synapse-dependent hooks
excluded from core.

neuron-dev-setup/templates/bin/soul-wrapper.sh.tmpl

@@ -0,0 +1,28 @@
+#!/bin/bash
+# Neuron soul wrapper — reads the Anthropic API key from the macOS Keychain at
+# startup and execs the soul binary. API keys are NEVER stored in plists or on
+# disk in plaintext. The Keychain is the single source of truth.
+#
+# The install.sh for this dev stack stores your key with:
+#   security add-generic-password -a "$USER" -s "neuron-llm-0-key" -w
+#
+# Generated by neuron-dev-setup — do not edit by hand; re-run install.sh instead.
+
+set -u
+
+# Primary inference key (Anthropic) — required.
+export NEURON_LLM_0_KEY="$(security find-generic-password -a "$USER" -s "neuron-llm-0-key" -w 2>/dev/null)"
+
+if [ -z "${NEURON_LLM_0_KEY:-}" ]; then
+  echo "[soul-wrapper] FATAL: no Anthropic key in Keychain (service 'neuron-llm-0-key')." >&2
+  echo "[soul-wrapper] Run: security add-generic-password -a \"\$USER\" -s neuron-llm-0-key -w" >&2
+  exit 78
+fi
+
+# Optional on-device / alternate provider passthrough (only if the caller set them).
+[ -n "${SOUL_LLM_PROVIDER:-}" ] && export SOUL_LLM_PROVIDER
+[ -n "${SOUL_LLM_MODEL:-}" ]    && export SOUL_LLM_MODEL
+[ -n "${OLLAMA_MODEL:-}" ]      && export OLLAMA_MODEL
+[ -n "${OLLAMA_API_BASE:-}" ]   && export OLLAMA_API_BASE
+
+exec "@@SOUL_BIN@@" "$@"