M1: Ollama chat loop — interactive CLI with LLM

[bug-ops]

Goal

User types a message in CLI, gets a response from Ollama. First proof-of-life for the agent.

Scope

• LlmProvider trait definition
• Ollama backend (ollama-rs)
• Config loading (TOML + env overrides)
• Agent loop with CLI I/O

Acceptance Criteria

• cargo run starts interactive session
• User types message, receives Ollama response
• Multi-turn conversation within session
• Ctrl+C exits cleanly
• Clear error if Ollama unreachable
• Config from config/default.toml, env var overrides work

Child Issues

• Define LlmProvider trait and core message types #8 Define LlmProvider trait and core message types
• Implement OllamaProvider using ollama-rs #9 Implement OllamaProvider using ollama-rs
• Implement config loading from TOML with env overrides #10 Implement config loading from TOML with env overrides
• Wire CLI agent loop: stdin -> Ollama -> stdout #11 Wire CLI agent loop: stdin -> Ollama -> stdout

Depends On

#1 (M0)