refactor: rename RoleDefinition fields for clarity

- identity → goal
- prepare → capabilities (string[])
- execute → procedure
- report → output
- outputSchema → meta

Fixes #364

examples/analyze-topic.yaml

@@ -3,22 +3,23 @@ description: "Single-role topic analysis using four-phase role description"
 roles:
   analyst:
     description: "Analyzes a given topic and produces a structured summary"
-    identity: |
+    goal: |
       You are a research analyst with expertise in breaking down complex topics
       into clear, structured summaries. You think critically and cite key points.
-    prepare: |
-      Review the topic carefully. Consider multiple perspectives and identify
-      the core question being asked.
-    execute: |
+    capabilities:
+      - research
+      - critical-thinking
+      - structured-writing
+    procedure: |
       Analyze the topic by:
       1. Identifying the main thesis or question
       2. Listing 3-5 key points with brief explanations
       3. Noting any counterarguments or caveats
       Keep your analysis concise (under 500 words).
-    report: |
+    output: |
       Provide your analysis as markdown under the frontmatter.
       The frontmatter must include your structured findings.
-    outputSchema:
+    meta:
       type: object
       properties:
         thesis: