feat(01-01): add Phase 1 deps and implement config/CLI loading

- Add signal-hook 0.4.3, toml 1.0.3, serde 1.0, clap 4.5 to Cargo.toml
- Create src/config.rs with Config struct (deny_unknown_fields, serde defaults)
- Implement load_config() with vault_path resolution relative to config file dir
- Implement resolve_config_path() using binary-adjacent bbs.toml as default
- Implement print_config_error() with BBS-themed error messages
- Implement detect_login_shell() and parse_cli() with argv[0] dash stripping
- Create src/terminal.rs with init_terminal(), restore_terminal(), install_panic_hook()
- Wire early startup path in src/main.rs before terminal initialization

Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "bbs-md"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+ratatui = "0.30.0"
+signal-hook = "0.4.3"
+toml = "1.0.3"
+serde = { version = "1.0", features = ["derive"] }
+clap = { version = "4.5", features = ["derive"] }