feat: enforce mandatory rationale and role in explore/diagnosis schema output

- Remove oneOf string option from relevant_files/affected_files, require structured objects
- Add required fields: rationale (minLength 10), role/change_type enum
- Add optional fields: discovery_source, key_symbols
- Update all caller commands with new format instructions and success criteria
- Fix consumer code: Map-based dedup, getPath() helper, path extraction
- Fix frontend: f.rationale || f.reason backward-compatible fallback

.ccw/workflows/cli-templates/schemas/explore-json-schema.json

@@ -1,7 +1,7 @@
 {
   "$schema": "http://json-schema.org/draft-07/schema#",
   "title": "Exploration Context Schema",
-  "description": "Code exploration results from cli-explore-agent for task context gathering",
+  "description": "Code exploration results from cli-explore-agent for task context gathering. Every file MUST include selection rationale.",
   "type": "object",
   "required": [
     "project_structure",
@@ -20,21 +20,54 @@
     },
     "relevant_files": {
       "type": "array",
+      "minItems": 1,
       "items": {
-        "oneOf": [
-          {"type": "string"},
-          {
-            "type": "object",
-            "required": ["path", "relevance"],
-            "properties": {
-              "path": {"type": "string", "description": "File path relative to project root"},
-              "relevance": {"type": "number", "minimum": 0, "maximum": 1, "description": "Relevance score 0.0-1.0 (0.7+ high, 0.5-0.7 medium, <0.5 low)"},
-              "rationale": {"type": "string", "description": "Brief explanation of why this file is relevant from this exploration angle"}
-            }
+        "type": "object",
+        "required": ["path", "relevance", "rationale", "role"],
+        "properties": {
+          "path": {
+            "type": "string",
+            "description": "File path relative to project root"
+          },
+          "relevance": {
+            "type": "number",
+            "minimum": 0,
+            "maximum": 1,
+            "description": "Relevance score 0.0-1.0 (0.7+ high, 0.5-0.7 medium, <0.5 low)"
+          },
+          "rationale": {
+            "type": "string",
+            "minLength": 10,
+            "description": "REQUIRED: Selection rationale explaining why this file is relevant to the exploration topic. Must be specific (not generic). Example: 'Contains AuthService.login() which is the entry point for JWT token generation' rather than 'Related to auth'"
+          },
+          "role": {
+            "type": "string",
+            "enum": [
+              "modify_target",
+              "dependency",
+              "pattern_reference",
+              "test_target",
+              "type_definition",
+              "integration_point",
+              "config",
+              "context_only"
+            ],
+            "description": "File's role relative to the task: modify_target=needs changes, dependency=imported by targets, pattern_reference=demonstrates patterns to follow, test_target=tests needing update, type_definition=types/interfaces used, integration_point=where new code connects, config=configuration, context_only=understanding only"
+          },
+          "discovery_source": {
+            "type": "string",
+            "enum": ["bash-scan", "cli-analysis", "ace-search", "dependency-trace", "manual"],
+            "description": "How the file was discovered: bash-scan=structural scan (rg/find/tree), cli-analysis=Gemini/Qwen semantic analysis, ace-search=ACE context engine, dependency-trace=import/export graph traversal, manual=directly specified in task"
+          },
+          "key_symbols": {
+            "type": "array",
+            "items": {"type": "string"},
+            "description": "Key symbols (functions, classes, types) in this file relevant to the task. Example: ['AuthService', 'login', 'TokenPayload']"
           }
-        ]
+        },
+        "additionalProperties": false
       },
-      "description": "File paths to be modified or referenced for the task. Prefer object format with relevance scores for synthesis prioritization."
+      "description": "Files relevant to the task. Every file MUST have structured rationale explaining its selection basis and role classification."
     },
     "patterns": {
       "type": "string",