v0.19.0

• v0.19.0
• Merge pull request #45 from YawLabs/feat/write-groups
• feat(meta): add tailscale_tool_groups so the agent can see why a tool is missing
• test(filter): close the write-gate coverage gaps a coverage pass found
• fix(filter): make the admin warning track risk, and split three lookalike causes
• feat(filter): scope writes to named areas with TAILSCALE_WRITE_GROUPS
• Merge pull request #44 from YawLabs/feat/diff-acl-access
• fix(acl): bound diff_acl_access in wall-clock time, and close coverage gaps
• feat(acl): add tailscale_diff_acl_access
• Merge pull request #43 from YawLabs/feat/meta-forced-approval
• feat(mcp): forced approval and result-size caps via _meta