Fix typos in comments and docs (no functional changes)

[fifalodm]

Summary

Fix spelling mistakes across comments and documentation. No functional or API changes.

What’s changed

• Rust comments and messages:
  • constraint_generation, compiler (IR buckets), program_structure, type_analysis
  • Examples: “subsitute”→“substitute”, “assigment”→“assignment”, “auxiliar”→“auxiliary”, “lenghts”→“lengths”, “perfom”→“perform”, “oppened”→“opened”, etc.
• Docs:
  • RELEASES.md: “assigment”→“assignment”
  • mkdocs/docs/index.md: “convertors”→“converters”
• C/ASM generators (comments only):
  • code_producers/src/wasm_elements/*.rs, code_producers/src/c_elements/*.rs: “differen/intances/de”→“different/instances/the”
  • code_producers/src/c_elements/*/fr.asm (comments): “Returs”, “seconf”, “substract*”, “comare”→“Returns”, “second”, “subtract*”, “compare”

Explicitly not changed

• Correct/intentional terms: wast (crate name), Groth16 (surname), Connexion/BusConnexion naming.
• Identifiers that would require refactors (e.g., signal_to_ocurrences) to avoid breaking changes.

Validation

• Build and lints pass locally.
• Only comments, doc strings, and Markdown were edited.