fix: enforce ESLint in CI and add a check-only lint script (#101)

[Marvelg256]

Problem

The @typescript-eslint/no-explicit-any rule is set to error in .eslintrc.js, and context/code-standards.md states it is "enforced by ESLint, not just documentation." However, CI had no lint step — only npm ci, npm run build, and npm test. A PR reintroducing any passed CI cleanly.

The existing lint script used --fix, which rewrites files locally and does not reliably exit non-zero on violations it cannot auto-fix. There was no check-only variant for CI.

The codebase is currently clean (all 32 explicit any usages removed on 2026-07-16, zero found in src/ today), but this was unprotected.

Changes

package.json

• Added lint:check script: eslint "{src,apps,libs,test}/**/*.ts" --max-warnings=0 (no --fix)
• lint script with --fix kept untouched for local developer use

.github/workflows/ci.yml

• Added Lint step (npm run lint:check) after Install dependencies and before Build, so a lint failure reports quickly

context/progress-tracker.md

• Entry for 2026-07-28 describing the change and why

Acceptance criteria verification

Criterion	Result
npm run lint:check exits non-zero when any in src/	✅ Exits 1 (verified: added const x: any = 1 to src/app.module.ts, got @typescript-eslint/no-explicit-any error, exit 1)
npm run lint:check does not modify files	✅ No --fix flag
CI runs lint:check on every PR to main	✅ Added as step in ci.yml (on: pull_request: [main])
Existing lint with --fix still works	✅ Unchanged
No ESLint rules added/removed/changed	✅ Scripts and CI only
Build passes	✅ npm run build exits 0
All tests pass	✅ 345/345 pass
No pre-existing violations	✅ npm run lint:check exits 0 before changes

Evidence that a violation fails CI

Locally verified by temporarily introducing const x: any = 1 into src/app.module.ts and running npm run lint:check:

/workspaces/StepFi-API/src/app.module.ts
  92:10  error  Unexpected any. Specify a different type  @typescript-eslint/no-explicit-any

✖ 1 problem (1 error, 0 warnings)

Exit code: 1 — the step will fail CI.

Closes #101