[kennytm]

fix #86

[kennytm]

PTAL @crazycs520

breaking change, but imo the existing usages broken by this are wrong anyway as explained in #86.

[Copilot]

🟢 Approval recommended

No active review issues remain for the changes to literal error-message handling and JSON-decoding state reset.

No open issues 🎉

What changed in this PR

Addresses #86 by keeping cause-derived and JSON-decoded error messages literal, preventing stale arguments from formatting them.

Changes:

• Removes arguments from FastGenWithCause and GenWithStackByCause, directing template formatting to the existing ByArgs methods.
• Clears formatting arguments and other local state after successful JSON unmarshalling.
• Updates tests for literal percent sequences, redaction, state reset, and preservation of existing errors on invalid JSON.

File	Description
normalize.go	Makes cause-based generators argument-free and clears arguments when copying cause text.
normalize_test.go	Updates cause-generation tests for literal messages and the revised API.
compatible_shim.go	Clears stale local state after successful JSON decoding.
compatible_shim_test.go	Adds state-reset, literal-message round-trip, and invalid-input tests.

_{Review effort: Balanced}

[kennytm]

separating this into 2 PRs.