Add scripts/check_explainer_count.py, wire into build-explainers.yml

[evanjain-dot]

Nothing cross-checked the plain-prose "N explainers" mentions scattered
across README.md, CONTRIBUTORS.md, METRICS.md, and ROADMAP.md against
the real count of explainers/*.md, so this class of drift could recur
silently. Uses a small, explicit list of exact regexes rather than a
fuzzy scan - METRICS.md's weekly log is full of legitimate historical
counts that a loose "N explainers" match would false-positive on.

Also fixes the drift the check immediately caught: CONTRIBUTORS.md's
maintainer bio still said "the bulk of the 39 explainers" against a
real count of 53.

Fixes #352

[vercel]

@evanjain-dot is attempting to deploy a commit to the yashkewlani2020-gmailcom's projects Team on Vercel.

A member of the Team first needs to authorize it.

[github-actions]

@yakew7 @ahmdkaml @Shreyash0712 - new PR touching a path you own, please review.

[ahmdkaml]

I can't find any issue

[Shreyash0712]

2 things -

Bug - I don't think you've taken the traction table in readme into account. Add that as well.

Improvement - can we automate it? Like if there is drift or mismatch - why not let the script automatically fix it instead of just raising an error? In fact I think we should leave it entirely on script only - why should a contributor need to manually make changes in readme and all those files?

@yakew7 your thoughts?

[yakew7]

Nice fix, but I don't think this accounts for README.md's own Traction table.

README.md:1169 has a separate "Explainers Published" row:

| Explainers Published | 47 |

which is a second, independent "current explainer count" claim in this same file - distinct from the "Show all 53 explainers" summary this PR's CHECKS list covers (README.md:778). It's currently stale too (47 vs the real count of 53), and check_explainer_count.py as written won't catch it going forward since its README regex only targets the "Show all N explainers" string.

Can you add a CHECKS entry for r"Explainers Published \| (\d+)" (or similar) and fix the current 47 -> 53 drift in the same table row?

[yakew7]

Okay! The bug seems to be fixed and since the improvement is out of scope of this issue i will just add it myself to either this branch or main directly

[Shreyash0712]

That's just static fix @evanjain-dot . You're working on script changes right?

[yakew7]

@Shreyash0712 heads up - I pushed a follow-up directly to main (aead1aa) after this merged, since it's small and I wanted to close the gap I'd flagged above right away: check_explainer_count.py now also covers the Traction table's "Explainers Published" row (was still stale at 47), and it gained a --fix mode (make fix-explainer-count) so a contributor doesn't have to hand-edit README/CONTRIBUTORS/METRICS/ROADMAP whenever the explainer count changes - CI still just checks, since a fork PR's token can't push a fix back anyway.

If you spot any problem with it, either open an issue and I'll take it, or just open a PR fixing whatever you want directly.