fix(build): restore CDS Shiki highlighting on the HANA publish path (#1657)

[jung-thomas]

Fixes #1657 — CDS code blocks render with braces highlighted as illegal characters.

Root cause

Hugo's render-codeblock.html maps ```cds → the Chroma SQL lexer as a placeholder (Chroma ships no CDS lexer) and tags the wrapper data-lang=cds. The SQL lexer flags CDS braces as illegal → <span class=err>{ (the red braces in the issue screenshot). scripts/highlight-cds.ts (Shiki + the community cds.tmLanguage.json grammar) is supposed to replace those blocks with correct CDS highlighting in a post-build pass.

That pass runs in build:all (local + deploy.yml), so a local build is correct. But rebuild-content.yml — the canonical DEV/PROD content publish path — builds Hugo directly (/tmp/hugo --source hugo --minify), not build:all, and never runs build:highlight. It was dropped from this path pre-#591 (see the comment in content-drift-check.yml). So every content rebuild republished the Chroma-SQL fallback straight to HANA.

Evidence: live cap-status-transition-flows = 0 shiki, 15 class=err, 3 data-lang=cds blocks; the locally-built page (via build:all) = 298 shiki, 0 language-sql, blocks correct. Same failure class as the island-manifest / vendor / explore / joule steps previously retrofitted into this workflow.

Changes

• rebuild-content.yml: add Highlight CDS code blocks (Shiki) step after the Hugo build, runs in all modes (slug-targeted included).
• rebuild-content-qa.yml: same, pointed at hugo/public-qa (the QA publishDir).
• scripts/highlight-cds.ts: accept --dir / HIGHLIGHT_DIR (default hugo/public) so the QA dir is supported; fail the run if the data-lang=cds marker is present but zero blocks matched — guards against silent markup drift regressing this again.

Verification

• Ran the edited script against a fixture reproducing the exact live broken markup → 1 block replaced, exit 0, output is <pre class="shiki …"> with braces as normal punctuation (no class=err, no language-sql).
• Verified the guard: marker present + 0 matched → exit 1 with a clear message.

Post-merge action required

This corrects the pipeline; it does not retroactively fix already-published HANA content. Once merged, trigger a full rebuild to republish with highlighting:

gh workflow run rebuild-content.yml --repo sap-tutorials/tutorials-ims --ref main -f mode=full