feat: terraform prompt generator, provider parameter matrix, and model penalties
- Add Terraform Prompt Generator: AI-powered structured prompt generation
with dedicated chat UI, curated model selection (7 models), conversation
history with persistent sessions, and OCI TF resource reference context
- Provider parameter matrix: segment API params per model/provider,
explicitly null unsupported params (freq/pres penalty, temperature)
to prevent OCI SDK serialization errors
- Add penalties flag to model catalog: only GPT-4.1/4.1-mini/4o support
frequency_penalty and presence_penalty
- Flat workspace enforcement: prohibit module blocks and duplicate
variable declarations in Terraform system prompt
- Prompt Generator history: sidebar panel with session persistence,
restore, rename/delete (agent_type tf-prompt)
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