[github-agentic-autofix]

Summary

Avoid integer overflow when sizing the slice used to format GitHub validation errors.

Why

A potentially large error count could overflow when incremented for the allocation capacity.

What changed

• Use the validation error count directly as the slice capacity.

MCP impact

• No tool or API changes
• Tool schema or behavior changed
• New tool added

Prompts tested (tool changes only)

• Not applicable (no tool changes).

Security / limits

• No security or limits impact
• Auth / permissions considered
• Data exposure, filtering, or token/size limits considered — avoids overflow in allocation sizing.

Tool renaming

• I am renaming tools as part of this PR (e.g. a part of a consolidation effort)
  • I have added the new tool aliases in deprecated_tool_aliases.go
• I am not renaming tools as part of this PR

Lint & tests

• Linted locally with ./script/lint — unavailable: golangci-lint download host could not be resolved.
• Tested locally with ./script/test

Docs

• Not needed
• Updated (README / docs / examples)