feat: build SDL backend on all host platforms

[Xavier Bernhardt (XavierBernhardt-Philips)]

Enable the preview.sdl target for any host build, not just Windows, so the SDL DirectDisplay can be used from Linux/macOS host applications.

• gate preview/sdl on EMIL_HOST_BUILD instead of EMIL_BUILD_WIN
• avoid taking the address of a temporary SDL_Rect in Convert(), which fails to compile under GCC/Clang with -Werror
• drop a duplicate Colour.hpp include

Current problem:

• X11 is now installed for CI runs, but there's nothing to install it for local machines / dev containers.

[github-actions]

✅⚠️MegaLinter analysis: Success with warnings

Descriptor	Linter	Files	Fixed	Errors	Warnings	Elapsed time
✅ ACTION	actionlint	5		0	0	0.18s
✅ ACTION	zizmor	5	0	0	0	1.73s
✅ CPP	clang-format	166	1	0	0	1.04s
✅ CPP	cppcheck	166		0	0	4.08s
✅ DOCKERFILE	hadolint	1		0	0	0.72s
✅ JSON	jsonlint	8		0	0	0.26s
✅ JSON	prettier	8	1	0	0	0.3s
⚠️ MARKDOWN	markdownlint	4	0	2	0	0.54s
✅ MARKDOWN	markdown-table-formatter	4	0	0	0	0.18s
✅ REPOSITORY	checkov	yes		no	no	24.89s
✅ REPOSITORY	git_diff	yes		no	no	0.02s
✅ REPOSITORY	grype	yes		no	no	42.99s
✅ REPOSITORY	ls-lint	yes		no	no	0.0s
✅ REPOSITORY	secretlint	yes		no	no	1.34s
✅ REPOSITORY	syft	yes		no	no	1.25s
✅ REPOSITORY	trivy	yes		no	no	12.88s
✅ REPOSITORY	trivy-sbom	yes		no	no	0.14s
✅ REPOSITORY	trufflehog	yes		no	no	2.27s
⚠️ SPELL	lychee	35		3	0	2.8s
✅ YAML	prettier	8	1	0	0	0.28s
✅ YAML	v8r	8		0	0	5.12s
✅ YAML	yamllint	8		0	0	0.59s

Detailed Issues

⚠️ SPELL / lychee - 3 errors

📝 Summary
---------------------
🔍 Total...........67
🔗 Unique..........61
✅ Successful......64
⏳ Timeouts.........0
🔀 Redirected......10
👻 Excluded.........0
❓ Unknown..........0
🚫 Errors...........3
⛔ Unsupported......3

Errors in .github/workflows/static-analysis.yml
[403] https://binaries.sonarsource.com/Distribution/sonar-scanner-cli/sonar-scanner-cli-$ (at 32:21) | Rejected status code: 403 Forbidden

Errors in CHANGELOG.md
[404] https://github.com/philips-software/amp-preview/compare/v1.0.0...v1.1.0 (at 15:4) | Rejected status code: 404 Not Found

Errors in CONTRIBUTING.md
[ERROR] https://confluence.atlas.philips.com/display/GITHUB/Contribution+Models (at 42:22) | Connection failed. Check network connectivity and firewall settings

Hint: Followed 10 redirects. You might want to consider replacing redirecting URLs with the resolved URLs. Use verbose mode (`-v`/`-vv`) to see redirection details.
Hint: You can configure accepted/rejected response codes with `-a` or `--accept`

⚠️ MARKDOWN / markdownlint - 2 errors

CHANGELOG.md:18 error MD024/no-duplicate-heading Multiple headings with the same content [Context: "Features"]
CHANGELOG.md:23 error MD024/no-duplicate-heading Multiple headings with the same content [Context: "Bug Fixes"]

Notices

📣 MegaLinter 9.5.0 is out! Discover the new features and security recommendations in the release announcement. (Skip this info by defining SECURITY_SUGGESTIONS: false)

See detailed reports in MegaLinter artifacts

Your project could benefit from a custom flavor, which would allow you to run only the linters you need, and thus improve runtime performances. (Skip this info by defining FLAVOR_SUGGESTIONS: false)

• Documentation: Custom Flavors
• Command: npx mega-linter-runner@9.5.0 --custom-flavor-setup --custom-flavor-linters ACTION_ACTIONLINT,ACTION_ZIZMOR,CPP_CPPCHECK,CPP_CLANG_FORMAT,DOCKERFILE_HADOLINT,JSON_JSONLINT,JSON_PRETTIER,MARKDOWN_MARKDOWNLINT,MARKDOWN_MARKDOWN_TABLE_FORMATTER,REPOSITORY_CHECKOV,REPOSITORY_GIT_DIFF,REPOSITORY_GRYPE,REPOSITORY_LS_LINT,REPOSITORY_SECRETLINT,REPOSITORY_SYFT,REPOSITORY_TRIVY,REPOSITORY_TRIVY_SBOM,REPOSITORY_TRUFFLEHOG,SPELL_LYCHEE,YAML_PRETTIER,YAML_YAMLLINT,YAML_V8R

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