Harden and refactor Bloblang WASM input handling (#329)

* Harden and refactor Bloblang WASM input handling

- Ensure all JSON input is recursively sanitized to native Go types (float64/int64), preventing json.Number from reaching Benthos/Redpanda Connect.
- Add robust fixNumbers/canonicalize/failsafe checks for both string and JS object payloads.
- Clean up and document code for clarity and maintainability.
- Confirm all playground and headless tests pass.

* Update blobl-editor/wasm/main.go

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* Fix linter

* Apply coderabbit suggestions

* Remove duplicate call to fixNumbers

* Update Bump header

* Fix linter

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Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

Author: JakeSCahill