fix: render QA task as strict XML

[randlee]

Summary

• remove the blanket {% autoescape false %} workaround from qa-template.xml.j2
• keep normal XML autoescaping for attributes
• wrap readable prompt text in CDATA
• use MiniJinja's explicit string | cdata_escape boundary
• add strict-render, adversarial XML, typed-value, legacy-string, and no-sc-compose fallback coverage

Scope

This is a surgical structural migration. Frontmatter/schema/defaults are unchanged except version 1.1.0 → 1.2.0; prompt prose and conditionals are preserved. No repository-specific language was introduced or rewritten.

Other XML template families remain separate work and should be migrated in independent reviewable layers.

sc-compose / MiniJinja practice

The .xml.j2 template keeps filename-aware autoescaping enabled. Attributes use the normal XML formatter. CDATA text uses string | cdata_escape: string preserves existing strings without JSON quote wrapping and coerces structured/numeric values; cdata_escape safely splits ]]> and marks only that boundary safe. This avoids blanket autoescape disabling, handwritten entities, and macro-related strict-validation diagnostics.

Validation

• final fresh Luna review: PASS with no findings
• sc-compose render --strict --check-render --json: zero error diagnostics
• realistic legacy strings remain verbatim
• typed numeric/list/map fields round-trip
• quotes, backslashes, newlines, < > &, Unicode, repeated ]]>
• ElementTree and xmllint strict parsing
• focused module: 16 tests / 23 subtests PASS with real sc-compose
• same focused module PASS through the no-sc-compose Jinja fallback
• just lint PASS
• just test PASS
• git diff --check

Stack

• depends on fix: escape report machine-status JSON #185 and fix: render carry-forward findings as arrays #184 (stack #186)