chore: add .editorconfig for consistent formatting

[andrei-hasna]

Objective

chore: add .editorconfig for consistent formatting

Add a standard root .editorconfig to open-gateway (github.com/hasna/gateway): root=true, UTF-8, LF line endings, insert a final newline, trim trailing whitespace, 2-space indent for JS/TS/JSON/YAML/MD (preserve trailing whitespace for *.md). Match the repo's prevailing existing style. Do NOT reformat existing files or change product code. Scope: the .editorconfig file only. Open a PR against the d

VERIFIED 2026-07-29 against this repository's HEAD via the GitHub contents API: there is NO .editorconfig in the repo, so this is still needed.
Add the root .editorconfig ONLY. Do NOT reformat any existing file and do NOT touch product code — the diff should be exactly one new file.
Before writing it, inspect the repo's prevailing style (indent width actually used in src/, whether files end with a trailing newline) so the file describes what the repo already does instead of imposing a new one.
Acceptance: bun install succeeds, bun run typecheck (if the repo has one) and bun test are still green, and git diff --stat against the base shows only .editorconfig. No network, no credentials needed.

Verification

• policy source: base add5710 (immutable commit — agent-proof)
• containment: env — allowlist env, non-login shell, run-scoped HOME (registry auth seeded for install)
• install: pass
• typecheck: pass
• build: pass
• test: pass
• doctor (ci): ok — 11 checks passed (1 advisory)

---

Run run_844155ce0d5c · backend codewith · task 48537225-725e-4a75-8bc4-48d19e300a65
🏭 Generated by @hasnaxyz/factory

---

^{Need help on this PR? Tag @codesmith-bot with what you need. Autofix is disabled.}

[andrei-hasna]

[REVIEW] GO — #22 @ fcee0c5 — lens: correctness+security+gates, reviewer Augustus (1 of 1)

What I ran:

• git log --oneline origin/main..HEAD: exit 0
• git diff origin/main...HEAD --stat: exit 0
• git diff origin/main...HEAD --name-status: exit 0
• git diff --find-renames --find-copies --full-index origin/main...HEAD -- .editorconfig: exit 0
• bun install: exit 0
• bun run typecheck: exit 0
• bun run build: exit 0
• bun test: exit 0; 241 pass, 0 fail
• git status --short --branch: exit 0; clean worktree on lane-pr22

What I read:

• Full PR diff for the only changed file, .editorconfig
• The added .editorconfig file itself
• Surrounding repository source/config that could make this change behaviorally relevant: package.json, .github/workflows/ci.yml, tsconfig.json, tsconfig.build.json, .gitignore, and the root repository layout

Blocking P0/P1 findings:

• None. The PR only adds a conventional root EditorConfig with LF, UTF-8, final newline, trailing-whitespace trimming, two-space indentation for JS/TS/JSON/YAML/Markdown, and a Markdown override preserving trailing whitespace. I found no reachable correctness, security, data integrity, unsafe mutation, rollback, or required gate failure.

Non-blocking follow-ups:

• None.