feat(autogen): add AG2-019, ambiguous tool name

[bradAGI]

Ports the ambiguous-name check to AutoGen. Claude SDK (CSDK-007), OpenAI (OAI-007), ADK (ADK-007), and MCP (MCP-003) all ship it; the newer packs had none.

The tool name sits directly beside the description in what the model sees, so it is half the selection signal — and a generic verb like process or handle spends that half on nothing. Each wrong pick costs a full round of the conversation — propose, execute, reply — so an ambiguous name spends the AG2-004 max_round budget rather than the chat reaching an answer.

Same name_in list as CSDK-007, so behavior stays consistent across packs.

Verification — engine built at main:

$ trustabl rules validate .
OK: 85 rule pack(s), 211 rule(s) valid under rule schema version 14

Fire (tool named process): includes AG2-019
Silent (same tool renamed summarize_invoice): AG2-019 absent

A note on scope. I drafted a fifth rule in this batch for the Vercel AI SDK and dropped it after testing: ToolDef.Name is deliberately empty for vercel_ai_tool, because the SDK derives a tool's name from the key in the tools: { ... } record rather than from the tool({...}) call. The engine asserts this directly —

// internal/analysis/ts_vercel_tools_test.go
if tl.Name != "" {
    t.Errorf("Name: got %q, want empty (Vercel derives name from the tools-record key)", tl.Name)
}

so every name-based predicate (name_in, name_has_prefix) is structurally inert for that pack — it also blocks a Vercel idempotency rule, which is why the pack has none. Back-filling Name from the record key at discovery time would unblock both. Happy to open that engine PR if it'd be useful.

Paired engine PR follows, mirroring the rule into testdata/rules-fixture/ with fire/silent cases.