Fix the two temporal defects the campaign scale run found

[tamnd]

M14 was about running the passes at breadth to find out what breaks, and the temporal pass over 40 real instruments broke invariant 6 nine times. None of the nine was a provision coming back from the dead, which is the only thing that check exists for.

The check was wrong

A repeal terminates more versions than it repeals. When one clause goes, every component above it gets a new version without that child, and the old version of each of them is terminated by the same repeal event. Read naively, an article that lost a clause looks like an article that was repealed and came back the same day. The corpus says so out loud: Quyết định 06/2001 had provisions repealed out of two of its articles by two later decisions, and the article that lost a clause of Nghị định 03/2003 did the same thing.

So the terminating event now has to have targeted the component itself or something above it. A repeal aimed at a descendant is a component being re-issued smaller and that is ordinary. Nine violations became three.

The first attempt at that test was a string prefix on the identifier and it only got as far as six. It missed the chapter and section case, for the same reason the second bug exists.

The builder was wrong

depthOrder took depth from the number of colons in the identifier. An article is numbered against its instrument and not against the chapter holding it, so Điều 9 of a decree is ...:article-9 whichever chapter it sits in, while the chapter and section around it are two segments deep. Counting segments made the container look deeper than its contents, so the section got its version written before the articles under it existed and its children came out as empty strings.

Nothing failed loudly. Corpus wide it was 210 dangling child links across 33 components, a chapter whose consolidated text assembles to nothing, and parent links broken in exactly the way invariant 6 reads as resurrection. Depth now comes from walking the parent chain, which is the thing that actually states the structure.

What the real layer says now

Same 2031 versions of 1971 components from the same 52 events, and:

• invariant 6: 9 violations before, 3 after the check fix, 0 after the builder fix
• empty child identifiers: 210 before, 0 after
• all nine invariants hold

Tests

TestAnArticleThatLostAClauseWasNotItselfRepealed covers the check, and TestCheckCatchesLifeAfterRepeal still passes, so a genuine resurrection is still caught.

TestAChapterHoldsTheArticlesUnderIt builds a document shaped the way most decrees are, a chapter holding a section holding articles, and asserts no version holds an empty child identifier and that an amendment at the bottom shows up in the chapter's text. Against the old code it fails with four empty identifiers and an empty chapter text.

Gate is clean: gofmt, go vet, golangci-lint 0 issues, and go test -race -cover green across all 27 packages.

Refs #18