fix(tools): allow read_file to access CLI workspaces directory

[nhokboo]

Summary

• Agents using the Claude CLI provider store working files in ~/.goclaw/cli-workspaces/<session>/
• When these agents call read_file on their own files, access was denied because cli-workspaces was not in the allowedPrefixes list
• Add ~/.goclaw/cli-workspaces to read_file allowed paths alongside the existing skills directories

Reproducing

Logs show repeated security.path_escape + read_file: access denied warnings:

security.path_escape path=/.goclaw/cli-workspaces/agent-xxx/file.md workspace=/.goclaw/workspace
read_file: access denied allowedPrefixes=[~/.goclaw/skills ~/.agents/skills ~/.goclaw/skills-store]

Test plan

• Verify agents can read files from their cli-workspaces after the fix
• Verify go build ./... and go vet ./... pass
• Confirm agents still cannot read sensitive dirs (~/.goclaw/data/, ~/.goclaw/sessions/)