Rewrite docs, fix critical bugs, add web dashboard and nc HTTP fallback

- Rewrite README.md and README_CN.md: install-first structure, feature
  checklist, collapsible sections, comparison table, use cases
- Fix install.sh: _is_command_available typo, uninstall awk precision,
  add extensions/ and agents/ state dirs, update ASCII banner
- Fix bashclaw: deduplicate status Config line, improve doctor HTTP
  server capability check with websocat > socat > nc hierarchy
- Add nc-based HTTP fallback in gateway for macOS (no extra install)
- Add web dashboard: ui/index.html, ui/style.css, ui/app.js
- Add REST API endpoints in gateway/http_handler.sh for dashboard
- Fix onboard wizard model name references

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: CrazyBoyM

README.md

@@ -222,12 +222,12 @@ cmd_status() {
   printf '=== bashclaw status ===\n'
   printf 'Version:    %s\n' "$BASHCLAW_VERSION"
   printf 'State dir:  %s\n' "$BASHCLAW_STATE_DIR"
-  printf 'Config:     %s\n' "$(config_path)"
-
-  if [[ -f "$(config_path)" ]]; then
-    printf 'Config:     found\n'
+  local cfg_file
+  cfg_file="$(config_path)"
+  if [[ -f "$cfg_file" ]]; then
+    printf 'Config:     %s\n' "$cfg_file"
   else
-    printf 'Config:     not found\n'
+    printf 'Config:     not found (run: bashclaw config init)\n'
   fi
 
   local gw_port
@@ -261,8 +261,24 @@ cmd_doctor() {
     fi
   done
 
-  # Check optional commands
-  local opt_cmds=(python3 uuidgen socat nc)
+  # Check gateway HTTP server capability
+  local http_server=""
+  if is_command_available websocat; then
+    printf '[OK]   websocat found (gateway: WebSocket + HTTP)\n'
+    http_server="websocat"
+  elif is_command_available socat; then
+    printf '[OK]   socat found (gateway: HTTP)\n'
+    http_server="socat"
+  elif is_command_available nc; then
+    printf '[OK]   nc found (gateway: basic HTTP fallback)\n'
+    http_server="nc"
+  else
+    printf '[WARN] No HTTP server tool found (websocat/socat/nc). Gateway will not serve HTTP.\n'
+    issues=$((issues + 1))
+  fi
+
+  # Check other optional commands
+  local opt_cmds=(python3 uuidgen)
   for cmd in "${opt_cmds[@]}"; do
     if is_command_available "$cmd"; then
       printf '[OK]   %s found (optional)\n' "$cmd"