v3.5.1: POMDP belief-state + value-of-information planner + grounded anti-hallucination

Partial observability is now first-class:

- belief.rs — property-graph world model; nodes (host/service/vuln/exploit/cred)
  carry a probability, not a boolean. Bayesian observation updates; per-node
  Shannon entropy; mean-uncertainty + recon-frontier. Black-box = diffuse priors
  that sharpen with observation; white-box collapses toward deterministic (MDP).
- pomdp.rs — value_of_information(), decide() (recon vs exploit falls out of
  belief entropy), and may_assert() — the mathematical anti-hallucination gate:
  no exploitability claim while the belief is diffuse (high entropy) → observe first.
- grounding.rs — verification engine, hard rule "no claim without a tool receipt":
  empirical grounding for black-box (raw HTTP/OOB/error markers), symbolic for
  white-box (file:line into reviewed source). Ungrounded claims demoted + flagged
  receipt_missing (feeds future reward shaping).
- pipeline.finish(): grounding gate before reporting + belief-uncertainty readout.
- bump 3.5.0 → 3.5.1; README documents the v3.5.1 belief/grounding architecture
  and the infra/bandit/reward roadmap.

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

neurosploit-rs/templates/report.typ

@@ -1,4 +1,4 @@
-// NeuroSploit v3.5.0 — Typst report template (blank, structured).
+// NeuroSploit v3.5.1 — Typst report template (blank, structured).
 //
 // The harness generates `report.typ` per run by prepending a `findings` array
 // and a `meta` dict, then including this template's rendering logic. This file
@@ -24,7 +24,7 @@
 
 #set page(margin: 2cm, numbering: "1", footer: context [
   #set text(size: 8pt, fill: gray)
-  NeuroSploit v3.5.0 · #meta.target · confidential
+  NeuroSploit v3.5.1 · #meta.target · confidential
   #h(1fr) #counter(page).display()
 ])
 #set text(font: ("Helvetica Neue", "Helvetica", "Arial"), size: 10pt)