Add durable configurable hypothesis budget accounting

config/budget.example.toml

@@ -0,0 +1,15 @@
+# Copy to ignored config/budget.local.toml. Frozen per analysis revision.
+# Integer investigation units, independent of model tokens and money.
+[budget]
+default_action_cost = 10
+max_reward_bps = 8000             # At most 80% refund; must remain below 10000
+new_evidence_score = 100          # Deterministic score for unseen nonempty JSON
+low_information_threshold = 20  # min(novelty, semantic) <= threshold is low gain
+max_low_information_steps = 3    # Consecutive settled low-gain actions
+
+# Examples for future tools; these do not implement or authorize tool execution.
+[budget.action_costs]
+"source.find_text" = 10
+"source.read_context" = 5
+"database.lookup" = 10
+"research.lookup" = 20