Add Wave contract schemas for pipeline validation

JSON Schema definitions for all pipeline handover contracts
including issue analysis, research, enhancement, and sync flows.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.wave/contracts/improvement-assessment.schema.json

@@ -0,0 +1,44 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "Improvement Assessment",
+  "description": "Structured assessment of code improvement opportunities",
+  "type": "object",
+  "required": ["target", "findings", "summary", "timestamp"],
+  "properties": {
+    "target": { "type": "string", "minLength": 1 },
+    "findings": {
+      "type": "array",
+      "items": {
+        "type": "object",
+        "required": ["id", "category", "title", "location", "description", "impact", "effort"],
+        "properties": {
+          "id": { "type": "string", "pattern": "^IMP-[0-9]{3}$" },
+          "category": {
+            "type": "string",
+            "enum": ["error_handling", "performance", "testability", "robustness", "maintainability", "code_quality"]
+          },
+          "title": { "type": "string", "minLength": 3 },
+          "location": { "type": "string", "minLength": 1 },
+          "description": { "type": "string", "minLength": 10 },
+          "current_code": { "type": "string" },
+          "suggested_fix": { "type": "string", "minLength": 5 },
+          "impact": { "type": "string", "enum": ["high", "medium", "low"] },
+          "effort": { "type": "string", "enum": ["trivial", "small", "medium", "large"] },
+          "risk": { "type": "string", "enum": ["none", "low", "medium", "high"] }
+        }
+      }
+    },
+    "summary": {
+      "type": "object",
+      "required": ["total_findings", "overall_quality"],
+      "properties": {
+        "total_findings": { "type": "integer", "minimum": 0 },
+        "by_category": { "type": "object" },
+        "quick_wins": { "type": "array", "items": { "type": "string" } },
+        "high_impact": { "type": "array", "items": { "type": "string" } },
+        "overall_quality": { "type": "string", "minLength": 10 }
+      }
+    },
+    "timestamp": { "type": "string", "format": "date-time" }
+  }
+}