Reposition README and project description for AI agents, not bots

Restructure README to put agent-critical information first: JSON
contract, exit codes, headless auth, and workflow patterns. Remove
"Bots" from title — this is a tool agents wield, not a chatbot
framework. Update Cargo.toml description and keywords for agent
discoverability.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: sionsmith

Cargo.toml

@@ -5,10 +5,10 @@ edition = "2021"
 rust-version = "1.75"
 license = "MIT"
 authors = ["OSO DevOps"]
-description = "A Rust CLI for Microsoft Teams — agent-first design"
+description = "Microsoft Teams CLI for AI agents — structured JSON output, deterministic exit codes, headless auth, real-time webhooks"
 repository = "https://github.com/osodevops/ms-teams-cli"
 readme = "README.md"
-keywords = ["teams", "microsoft", "cli", "graph-api", "mcp"]
+keywords = ["teams", "microsoft", "ai-agent", "graph-api", "mcp"]
 categories = ["command-line-utilities"]
 
 [[bin]]