docs(specs): kick off authorization-obligations (brief + requirements, unapproved)

Absence bugs as obligations rather than flows: obligated operations and
discharger kinds as closed facts, obligation shapes learned from trusted
pairs, the application's policy recovered from sibling-handler
consistency and an optional declared policy file, path-aware evaluation
with a function-local degraded mode, honest rungs below proof, an
`obligations` improve lever under the holdout gate. Depends on
reachability-flow-model and guard-dominance-regime; the roadmap marks
reachability as the critical path for two consumers.

Co-Authored-By: Claude Fable 5.1 <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG

.kiro/specs/authorization-obligations/spec.json

@@ -0,0 +1,27 @@
+{
+  "feature_name": "authorization-obligations",
+  "created_at": "2026-09-05T17:00:00Z",
+  "updated_at": "2026-09-05T17:00:00Z",
+  "language": "en",
+  "phase": "requirements-generated",
+  "approvals": {
+    "requirements": {
+      "generated": true,
+      "approved": false
+    },
+    "design": {
+      "generated": false,
+      "approved": false
+    },
+    "tasks": {
+      "generated": false,
+      "approved": false
+    }
+  },
+  "ready_for_implementation": false,
+  "depends_on": [
+    "reachability-flow-model",
+    "guard-dominance-regime",
+    "corpus-seeded-mechanisms"
+  ]
+}