fix(parser): surface diagnostic when end tag skips an unclosed child

[Brooooooklyn]

Summary

• Closes the template portion of Invalid templates produce no diagnostic (parse errors swallowed) #290 — <div><span></div> (and similar malformed templates) now produces an Unexpected closing tag "div" diagnostic in result.errors / result.diagnostics instead of compiling silently.
• Mirrors Angular's reference _popContainer (ml_parser/parser.ts), which tracks whether any implicitly-closed container above the match required an explicit end tag and surfaces a diagnostic on the offending end tag.
• Recovery is unchanged — the outer element is still added to the AST so downstream stages keep working.

Why this was broken

pop_element_container was popping skipped containers above the match without distinguishing optional-end-tag elements (<li>, <td>, etc.) from ones that legitimately need an end tag. So </div> closing past an open <span> was treated the same as </ul> closing past an open <li> — completely silent.

Test plan

• cargo test — 2559 passed, 0 failed
• New unit tests in crates/oxc_angular_compiler/src/parser/html/parser.rs:
  • test_parse_unclosed_inner_tag_reports_error — the exact repro from the issue
  • test_parse_mismatched_close_does_not_error_for_optional_end_tag — <ul><li>...</ul> stays silent
  • test_parse_multiple_unclosed_inner_tags_reports_error — </section> skipping past <div> and <span>
• New integration test test_malformed_template_surfaces_parse_diagnostic compiling the BadComponent from the issue and asserting the diagnostic propagates to the file-level transform result
• cargo fmt --all -- --check clean

Out of scope

The issue also mentions ambiguous DI unions (A | B) — that's a separate code path (util/type_extract.rs::resolve_di_token_type) and worth its own PR.

🤖 Generated with Claude Code

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Note

Low Risk
Localized parser diagnostic logic with recovery unchanged; covered by new unit and integration tests.

Overview
Malformed templates where a closing tag skips still-open children (e.g. <div><span></div>) now emit an Unexpected closing tag diagnostic on that end tag instead of compiling with empty errors, aligned with Angular’s _popContainer behavior.

pop_element_container now returns whether any implicitly closed container above the match required an explicit end tag—using closed_by_parent for elements and always treating @blocks as non-silent—while HTML5 auto-close from a new opening tag stays unchanged. Optional-end-tag cases like <ul><li>…</ul> remain error-free, and recovery still builds the outer AST. An integration test asserts the diagnostic reaches file-level transform_angular_file results.

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