feat: add unified update_claude_comment tool

- Add new update_claude_comment tool that automatically handles both issue and PR comments
- Remove individual update_issue_comment and update_pull_request_comment tools
- Pass CLAUDE_COMMENT_ID, GITHUB_EVENT_NAME, and IS_PR to MCP server environment
- Simplify Claude's comment update workflow by removing need for owner/repo/commentId params
- Update prompts and tests to use the new unified tool

src/mcp/install-mcp-server.ts

@@ -1,12 +1,16 @@
 import * as core from "@actions/core";
 
-export async function prepareMcpConfig(
-  githubToken: string,
-  owner: string,
-  repo: string,
-  branch: string,
-  additionalMcpConfig?: string,
-): Promise<string> {
+type PrepareConfigParams = {
+  githubToken: string;
+  owner: string;
+  repo: string;
+  branch: string;
+  additionalMcpConfig?: string;
+  claudeCommentId?: string;
+};
+
+export async function prepareMcpConfig(params: PrepareConfigParams): Promise<string> {
+  const { githubToken, owner, repo, branch, additionalMcpConfig, claudeCommentId } = params;
   try {
     const baseMcpConfig = {
       mcpServers: {
@@ -36,6 +40,9 @@ export async function prepareMcpConfig(
             REPO_NAME: repo,
             BRANCH_NAME: branch,
             REPO_DIR: process.env.GITHUB_WORKSPACE || process.cwd(),
+            ...(claudeCommentId && { CLAUDE_COMMENT_ID: claudeCommentId }),
+            GITHUB_EVENT_NAME: process.env.GITHUB_EVENT_NAME || "",
+            IS_PR: process.env.IS_PR || "false",
           },
         },
       },