fix: OS release prep - bootstrap script, deps, docs

- Fix bootstrap script (.env.example.local → .env.example)
- Fix @langchain/core version conflict (^1.0.1 → ^0.3.0)
- Add settings:open event listener for LocalKeyGate button
- Pin Next.js to 15.1.3 (was "latest")
- Default runtime to 'local' mode
- Remove desktop app references from UI text
- Rewrite MCP docs for web-only context
- Add SECURITY.md, CODE_OF_CONDUCT.md, CHANGELOG.md
- Add docs/README.md, docs/TROUBLESHOOTING.md
- Update README with platform support table

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

scripts/dev/bootstrap-local.sh

@@ -3,7 +3,7 @@ set -euo pipefail
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 REPO_DIR="$(cd "${SCRIPT_DIR}/../.." && pwd)"
-ENV_TEMPLATE="${REPO_DIR}/.env.example.local"
+ENV_TEMPLATE="${REPO_DIR}/.env.example"
 TARGET_ENV="${REPO_DIR}/.env.local"
 SQLITE_SEED_SCRIPT="${REPO_DIR}/scripts/database/sqlite-ensure-app-schema.sh"
 
@@ -12,7 +12,7 @@ log() {
 }
 
 if [ ! -f "$ENV_TEMPLATE" ]; then
-  echo "Error: ${ENV_TEMPLATE} not found. Make sure .env.example.local exists." >&2
+  echo "Error: ${ENV_TEMPLATE} not found. Make sure .env.example exists." >&2
   exit 1
 fi