Retire referencePending: gocsvj enforces §1 rules

[peo-machine]

Summary

gocsvj#12 (merged) shipped strict §1 structural-rule enforcement in the reference Go implementation. The six skip-list entries in conformance_test.go's referencePending map can now retire:

Vector	Spec rule	gocsvj behavior
05-empty-header-line (accept)	§1 rule 1: single \n is the minimum valid file	now accepts
05-missing-trailing-newline (reject)	§1 rule 2: trailing newline required	now rejects
06-ragged-row-short (reject)	§1 rule 3: every row matches header width	now rejects
07-ragged-row-long (reject)	§1 rule 3	now rejects
08-duplicate-header-names (reject)	§1 rule 4: header names pairwise distinct	now rejects
09-duplicate-empty-header (reject)	§1 rule 4	now rejects

Changes

• Bumps gocsvj pin in go.mod to master (post-#12 — v0.0.0-20260526150927-654752620b64).
• Removes the referencePending map and its two skip clauses from conformance_test.go.
• Removes the "Reference impl pending list" subsection from README.md — no entries left to document.

After this PR, the Go runner exercises every vector against gocsvj with no skips, matching what other-language implementers are already expected to do.

Verified locally

$ go test -v ./...
=== RUN   TestInputs
    --- PASS: TestInputs/01-simple-strings  …  07-trailing-empty-string  (7/7)
=== RUN   TestMustReject
    --- PASS: TestMustReject/01-empty-file  …  18-unescaped-control-char (18/18)
PASS
ok      github.com/csvj-org/conformance

Test plan

• CI green on the PR (the conformance workflow itself runs go test ./...).
• After merge: gocsvj's downstream conformance CI step (added in gocsvj#11) continues to pass on subsequent gocsvj PRs without skips.

🤖 Generated with Claude Code