feat: add Agent SDK support with USE_AGENT_SDK feature flag (#698)

* feat: add Agent SDK support with USE_AGENT_SDK feature flag

Add a feature-flagged code path that uses the Agent SDK instead of
spawning the CLI as a subprocess. When USE_AGENT_SDK=true is set,
the new SDK path is used; otherwise, existing CLI behavior is unchanged.

Changes:
- Add parse-sdk-options.ts for parsing ClaudeOptions into SDK format
- Add run-claude-sdk.ts for SDK execution with query() function
- Update run-claude.ts with feature flag check at entry point
- Update update-comment-link.ts to handle both cost_usd and total_cost_usd
- Add @anthropic-ai/claude-agent-sdk dependency

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

* refactor: simplify SDK types by using @anthropic-ai/claude-agent-sdk types directly

- Remove duplicate SdkRunOptions and McpStdioServerConfig types
- Use SDK's Options and McpStdioServerConfig types directly
- Return { sdkOptions, showFullOutput, hasJsonSchema } from parseSdkOptions
- Remove unnecessary convertMcpServers function
- Net reduction of ~70 lines

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

* refactor: use extraArgs for claudeArgs pass-through to CLI

Simplify option parsing by converting claudeArgs to extraArgs record
and letting the SDK/CLI handle --mcp-config, --json-schema, etc.

- Remove extractJsonSchema and parseMcpConfigs functions
- Add parseClaudeArgsToExtraArgs for simple flag parsing
- CLI handles complex args like --mcp-config directly

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

* ci

* refactor: remove hardcoded permission bypass flags

The SDK path should match CLI path behavior - permissions are handled
by the CLI itself, not hardcoded in the action.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

* chore: add logging for SDK vs CLI path selection

---------

Co-authored-by: Claude <noreply@anthropic.com>

src/entrypoints/update-comment-link.ts

@@ -152,7 +152,7 @@ async function run() {
 
     // Check if action failed and read output file for execution details
     let executionDetails: {
-      cost_usd?: number;
+      total_cost_usd?: number;
       duration_ms?: number;
       duration_api_ms?: number;
     } | null = null;
@@ -179,11 +179,11 @@ async function run() {
             const lastElement = outputData[outputData.length - 1];
             if (
               lastElement.type === "result" &&
-              "cost_usd" in lastElement &&
+              "total_cost_usd" in lastElement &&
               "duration_ms" in lastElement
             ) {
               executionDetails = {
-                cost_usd: lastElement.cost_usd,
+                total_cost_usd: lastElement.total_cost_usd,
                 duration_ms: lastElement.duration_ms,
                 duration_api_ms: lastElement.duration_api_ms,
               };

src/github/operations/comment-logic.ts

@@ -1,7 +1,7 @@
 import { GITHUB_SERVER_URL } from "../api/config";
 
 export type ExecutionDetails = {
-  cost_usd?: number;
+  total_cost_usd?: number;
   duration_ms?: number;
   duration_api_ms?: number;
 };