docs(init): validate specification

Establish v0.4 refinement-only NFR milestone. Tags run on v0.3.x line.
Scope sourced from v0.3 forward-references (REVIEW P2/A-304, AUDIT §193,
GRILL G-014, D-046): REQ-029 lexicon shared helper, REQ-030 cross-const
test, REQ-031 lifecycle type review, REQ-032 docs build CI. Zero feat:
phases by construction.

---ci---
project: oy
phase: 0
milestone: v0.4
status: specify
tag_base: v0.3.x
milestone_type: nfr
---/ci---

.ciagent/config.json

@@ -6,9 +6,9 @@
     }
   ],
   "active_project": "oy",
-  "milestone": "v0.3",
-  "milestone_type": "feature",
-  "tag_base": "v0.2.x",
+  "milestone": "v0.4",
+  "milestone_type": "nfr",
+  "tag_base": "v0.3.x",
   "autonomy": {
     "level": "full",
     "escalation_hooks": ["deploy", "delete_data", "merge_to_main"],