feat: allow gitea.issue.comment for author and reviewer profiles (#137)

- Add aliases 'issue.comment' and 'issue_comment' to GITEA_OPERATION_ALIASES so short names normalize to gitea.issue.comment
- Grant 'issue.comment' (and short) in v2 example profiles for example-author and example-reviewer
- Grant in gitea-mcp.example.json mdcps-reviewer
- Update docs example profiles
- Add test coverage for new aliases and normalization

This enables gitea_create_issue_comment and list for profiles that include it, while preserving fail-closed for others and separation of duties (issue.comment does not imply pr.review etc).

Closes #137

gitea-mcp.v2-contexts.example.json

@@ -41,7 +41,7 @@
       "execution_profile": "example-author",
       "audit_label": "example-author",
       "auth": { "type": "keychain", "id": "example-gitea-author-token" },
-      "allowed_operations": ["read", "branch", "commit", "push", "open_pr", "comment"],
+      "allowed_operations": ["read", "branch", "commit", "push", "open_pr", "comment", "issue.comment"],
       "forbidden_operations": ["approve", "request_changes", "merge"]
     },
     "example-reviewer": {
@@ -52,7 +52,7 @@
       "execution_profile": "example-reviewer",
       "audit_label": "example-reviewer",
       "auth": { "type": "keychain", "id": "example-gitea-reviewer-token" },
-      "allowed_operations": ["read", "review", "comment", "approve", "request_changes", "merge"],
+      "allowed_operations": ["read", "review", "comment", "issue.comment", "approve", "request_changes", "merge"],
       "forbidden_operations": ["branch", "commit", "push", "open_pr"]
     }
   },