v3.5.1 fix: critical char-boundary panic (was dropping findings) + background runs, progress bar, severity colors, /help

CRITICAL BUG: truncate()/source-context slices cut strings by BYTE, panicking on
a multibyte char (e.g. '—'). The panic crashed agent tasks → task.await returned
JoinError → unwrap_or_default() → empty RunOutput. Result: real confirmed findings
(win.ini traversal, HTML injection) were silently lost, workdir was empty, report
missing. Now all string truncation is char-safe (models.rs, pipeline.rs, repl.rs).

Also:
- Background runs: /run now runs in the BACKGROUND via rustyline's ExternalPrinter
  — the REPL keeps accepting commands while the engagement streams live. New
  /status (live phase + progress bar + findings) and /stop (graceful). Findings
  persist to history + report on completion (finalize_run ensures workdir is set
  even on abort, fixing "no report file in ").
- Progress bar: agents-done/total with %, shown in /status.
- Severity colors in the live feed (Critical=red…Info=grey); confirmed vote = green.
- /help reformatted into clear aligned sections.
- TUTORIAL: document non-blocking runs, /status progress, /stop, colors.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

neurosploit-rs/.neurosploit/history.txt

@@ -11,3 +11,14 @@ run
 /reports
 /report
 /exit
+/show
+/run
+/results
+/report
+/help
+/results
+/target http://testasp.vulnweb.com/
+/run
+/results
+/report
+/exit

neurosploit-rs/.neurosploit/runs.json

@@ -5,5 +5,19 @@
     "target": "https://redteamleaders.com",
     "workdir": "",
     "findings": []
+  },
+  {
+    "id": 2,
+    "mode": "black-box",
+    "target": "https://redteamleaders.com",
+    "workdir": "",
+    "findings": []
+  },
+  {
+    "id": 3,
+    "mode": "black-box",
+    "target": "http://testasp.vulnweb.com/",
+    "workdir": "",
+    "findings": []
   }
 ]

neurosploit-rs/.neurosploit/session.json

@@ -6,7 +6,7 @@
   "mcp": false,
   "vote_n": 3,
   "max_agents": 0,
-  "target": "https://redteamleaders.com",
+  "target": "http://testasp.vulnweb.com/",
   "repo": null,
   "auth": null,
   "creds": null,