Add Publisher v2 + 5 extracted skills

Publisher fixes:
- Checkout new branch before push (was pushing main ref)
- Verify files staged before commit
- Handle duplicate files gracefully
- Clean error reporting per stage

Skills merged to main:
- mcp-server-setup (from pipeshub-ai)
- research-pipeline (from Blacknode)
- multi-agent-sequential-workflow (from Fast-LLM-Agent-MCP)
- unifai-workflow-execution (from UnifAI)
- code-review-agent-workflow (from AgentKit)

skills/code-review-agent-workflow/examples.md

@@ -0,0 +1,10 @@
+# Examples: code-review-agent-workflow
+
+## Usage Example
+
+```python
+# How to use this skill
+# Inputs: Sample diff of code changes (str), Repo context (dict)
+# Process: Step 1: Build the graph for the code review agent using `build_graph()` from `agentkit.workflow.code_review.graph` → Step 2: Invoke the graph with initial parameters including sample diff, repo context, user ID, and other metadata → Step 3: The graph processes the input through a series of steps, generating messages and issues as it progresses
+# Outputs: Final result containing processed messages and issues (dict)
+```