fix(macros): #[tool] now emits array/object schemas and rejects unsupported types

[Fullstop000]

Closes #235.

#[tool] previously mapped every non-scalar parameter type to "string" in the generated JSON schema. This fix:

• Vec<T> / [T; N] → {"type": "array", "items": ...}
• HashMap / BTreeMap and structs/enums → {"type": "object"}
• References, slices, tuples and other unsupported types are rejected at compile time instead of silently degrading to "string".

Added integration tests in ignis/tests/tool_macro.rs and a compile_fail doctest.

Checklist:

• cargo fmt --all -- --check
• cargo clippy --workspace --all-targets -- -D warnings
• cargo test --workspace
• cargo build --release
• Secret scan clean