Fix type specs to accept structs and atom-keyed maps

[xu-chris]

Summary

Fixes Dialyzer warnings when calling Toon.encode!/1 with structs or maps with atom keys.

Problem

The Toon.Types.encodable() type only accepted:

• %{optional(String.t()) => encodable()} (string-keyed maps)

But users commonly pass:

• Ecto schemas (structs with atom keys like %Screentour.Festivals.Edition{})
• Maps with atom keys (%{name: "Alice"})

The Toon.Encoder protocol handles normalization, but Dialyzer didn't know this.

Solution

• Add Toon.Types.input() as term() - the Encoder protocol accepts any type with an implementation
• Update encode/1,2 and encode!/1,2 specs to use input() for parameters
• Keep encodable() for documenting the normalized output format

TDD Process

RED: Created lib/toon/type_check.ex that calls Toon.encode!/1 with a struct. Dialyzer failed:

The call 'Elixir.Toon':'encode!'(#struct) will never return since it differs in the 1st argument

GREEN: Added input() type and updated specs. Dialyzer passes.

REFACTOR: Removed temporary test module, kept behavioral tests in encoder_test.exs.

Test plan

• 549 tests pass
• mix quality.ci passes (credo, dialyzer, format)
• New tests verify struct and atom-key encoding via public API

🤖 Generated with Claude Code

[coveralls]

Pull Request Test Coverage Report for Build 45581c8dffdd6a4b56077620d5c1a98ec683ef47-PR-14

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 67.867%

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Totals
Change from base Build 039bd55701dad23196695fb4d7e40f621ccfb962:	0.0%
Covered Lines:	716
Relevant Lines:	1055

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💛 - Coveralls