docs: fix article typo in ARCHITECTURE.md

[nelsondeleonc-source]

Summary

• Fixes a small grammar issue in the "Adding a new language extractor" section: "Add a extract_<lang>..." should be "Add an extract_<lang>..." since the identifier starts with a vowel sound.

Test plan

• Docs-only change, no functional impact.

[graphify-labs]

Graphify reviewed this change.

Looks safe to merge — no coupling regressions and no blocking issues, checked against the code graph (not a self-assessment).

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Graphify review — findings

This pull request makes a single-character grammar edit in ARCHITECTURE.md, changing "a extractor" to "an extractor" in the "Adding a new language extractor" section. It is a documentation-only wording fix with no code or behavioral changes.

No blocking issues surfaced.

Analysis details — impact, health, verification

Impact & health

Graphify review

Impact — 9 functions depend on the 9 functions this change touches.

Health — grade A; no new coupling hotspots.

Verification — 9 functions in the blast radius were not formally verified this run (proofs are advisory here).

Gate & verification

graphify gate

PASS — objectively clean (no health regressions, tests not run — proofs not run this pass (advisory)). Grounded, not self-assessed.

Advisory (not blocking):

• verification_scope: 9 function(s) in the blast radius were not formally verified this run