docs: add plain-language identification-pipeline walkthrough

[WilfordGrimley]

Description

Adds docs/identification-pipeline.md — the owner-approved, plain-language walkthrough of the printing-identification pipeline (Stage C evidence extraction, Stage D join-key calculator, the human-backed vote gate), as a companion to docs/theory.md (which proves the false-accept bound formally; this one explains the mechanics).

• New file: docs/identification-pipeline.md, sourced from the owner-approved walkthrough text, preserved verbatim except:
  • one factual correction: the g5 bullet's "12,684 gate-checked votes" is actually a card count (the union of cards touched across both the printing- and tag-consensus engines, per docs/reports/2026-07-21-recovery-arc.md), not a vote count — fixed to "12,684 gate-checked cards" rather than softened or left as-is.
  • "Until today it wrongly vetoed..." reworded to "Until the Proxy-marker weaken-don't-withhold + OCR pre-classification short-circuit #294 re-scan it wrongly vetoed..." since this is now a standing reference doc, not a point-in-time note, and "today" would go stale silently.
• Cross-links added both ways: theory.md's intro now points to it for the plain-language version (one line, in place); the new doc points to theory.md§7 (the deduction-chain composition) and to docs/features/printing-tags.md / docs/features/catalog-completion-plan.md (the systems it feeds into).
• Added to CLAUDE.md's flat docs/ index and docs/README.md's "Understanding the system" map, both directly under the theory.md entry.
• Spot-checked every cited fact/number against the current repo state (all confirmed accurate, no drift found): Proxy-marker weaken-don't-withhold + OCR pre-classification short-circuit #294 commit (86fca804) confirms the 99.7% short-circuit rate and the 1,552 wrongly-vetoed proxy-marker matches; Fix collector-line parser mistaking glued denominator+rarity for set code #260/Fix proxy-marker regex to match plural/passive forms #280/Add playtest family to proxy-marker regex #285/Add review-queue clustering + batch no-match confirmation API (#262) #265/Downgrade AI-Generated tag from sensitive back to standard #292 all resolve to real merged commits with matching descriptions; "Marked as proxy" tag + marker-absence moderation flags (catalog compliance scan) #291 ("Marked as proxy", cited as "planned") is confirmed open, unimplemented, matching that description exactly; the 2/20,677 ambiguous-tiebreak rate matches theory.md§7a and docs/reports/2026-07-21-staged-write.md exactly.

Wiki/site placement (recommendation, not unilaterally decided beyond wiki)

Added docs/identification-pipeline.md to .github/wiki-publish-map.json with targets: ["wiki"] (wiki page name Identification-Pipeline), directly under theory.md's own entry — this matches every other "Understanding the system" entry's current pattern (wiki-only) except overview.md.

Did NOT add a "site" target. docs/documentation-process.md states theory.md and self-hosting.md "remain per this proposal's proposed initial mapping" for the site pipeline — i.e. they're named as next-in-line for site but that widening hasn't happened yet. Adding site to this new companion page ahead of theory.md itself getting it would jump the owner's own stated sequencing. Recommend: if/when theory.md gets widened to ["wiki", "site"], add this page in the same pass (e.g. sitePath: "/guide/how-cards-get-identified").

Checklist

• I have installed pre-commit and installed the hooks with pre-commit install before creating any commits.
• I have updated any related tests for code I modified or added new tests where appropriate. — N/A, docs-only change.
• I have manually tested my changes as follows:
  • python3 .github/scripts/docs_lint.py — clean.
  • python3 .github/scripts/tests/test_publish_wiki_link_rewrite.py — 4 tests, OK.
  • python3 .github/scripts/tests/test_publish_readme.py — 8 tests, OK.
  • python3 .github/scripts/publish_readme.py . regenerate-and-diff against committed readme.md — no diff (this change doesn't touch a README-REGION source, as expected).
  • npx prettier@2.7.1 --check on every touched file — clean.
• I have updated any relevant documentation or created new documentation where appropriate. (This PR is that update: CLAUDE.md, docs/README.md, docs/theory.md, .github/wiki-publish-map.json.)

Merge-time checklist item

• wiki: Identification-Pipeline needs creating on next docs-wiki-publish run (automatic once merged — docs/identification-pipeline.md is now in .github/wiki-publish-map.json). Owner: consider widening to site target together with theory.md per the recommendation above.