Integrates ported qt6-grantlee5-files-parser into build pipeline

Entire-Checkpoint: 01M1PAC5S1VHGY9QR6Q0K6VSQP

grantlee-parser-toktexttemplate-porting.prompt.md

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+Implement a Qt6 replacement for the legacy Qt5/Grantlee5 CodeGen parser and integrate it into the Qt6 build flow.
+
+Context:
+- Legacy parser A (Qt5 + Grantlee5):
+  `./qt-migration-legatus/qt5-before/qt5-legatus-legacy/Lts/Common/CodeGen`
+- Replacement parser B (Qt6 + KTextTemplate):
+  `./qt-migration-legatus/qt6-after/qt6-migrated-legatus/Lts/Common/CodeGen`
+- Docker build entry:
+  `./app/Dockerfile`
+- Relevant macros:
+  - `./qt-migration-legatus/qt5-before/qt5-legacy-legatus/cmake/MacroCodeGenIdl.cmake`
+  - `./qt-migration-legatus/qt6-after/qt6-migrated-legatus/cmake/MacroCodeGenIdl.cmake`
+
+Goals:
+1. Analyze how A is built and invoked in the Qt5 flow.
+2. Make B build reproducibly via `./app/Dockerfile` with Qt6 + KTextTemplate.
+3. Find all relevant `*grantlee*` input files and test B against all of them.
+4. Fix/extend B only as needed to support real repository inputs.
+5. Integrate B into the Qt6 codegen/build flow based on how A is invoked.
+6. Update the relevant CMake/macro wiring.
+7. Preserve existing Qt6 migration work.
+
+Requirements:
+- Use Docker for building B.
+- Use Docker to create and remove folders/files
+- Inspect real call sites before changing integration.
+- Keep changes small and reviewable.
+- Touch Qt5-side files only if needed for analysis/comparison/minimal build clarity.
+- If Grantlee behavior cannot be matched exactly in KTextTemplate, implement the best practical transitional solution and document remaining gaps.
+- `./qt-migration-legatus/qt5-before/qt5-legacy-legatus` is read-only
+
+Done when:
+- B builds successfully through `./app/Dockerfile`
+- all relevant `*grantlee*` inputs were tested with B
+- Qt6 build flow uses B instead of Grantlee5 dependency
+- macro/CMake integration is updated
+- remaining incompatibilities are documented
+- provide a concise summary of changed files, test results, and open gaps
+- commit and push in `./qt-migration-legatus/qt6-after/qt6-migrated-legatus` after user feedback