Define initial state for Phase C5 formal model

Author: iamfurydammit

formal/INIT-STATE.md

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+# XSTRP Phase C5 — Initial State Definition
+
+## Purpose
+
+This document defines the initial conditions for the Phase C5
+formal verification model of XSTRP.
+
+The initial state represents the moment immediately after an intent
+is created, before any authorization, proof submission, or expiry.
+
+---
+
+## Initial Conditions
+
+At model start, the following conditions hold:
+
+- intent_state = Created
+- authorization_valid = FALSE
+- proof_present = FALSE
+- is_expired = FALSE
+
+No other state is permitted as an initial condition.
+
+---
+
+## Rationale
+
+The Created state is the only valid protocol entry point.
+
+At creation time:
+- No authorization has yet been satisfied
+- No proof artifacts exist
+- The intent has not expired
+
+All other states must be reached through explicit transitions
+defined in the protocol.
+
+---
+
+## Exclusions
+
+- No transition is assumed at initialization
+- No implicit authorization exists
+- No implicit expiry exists
+- No terminal state is reachable at initialization
+
+---
+
+## Status
+
+Initial state defined.
+No transitions specified yet.