Ignore fragment-only links when naming the front page

[chubes4]

Summary

Updated front-page navigation label selection so same-page fragment links do not supply the page name. When there is no eligible hash-less link, existing title fallbacks can apply.

What changed

• Changed `ArtifactCompiler::entryNavigationLabel()` to return only a hash-less navigation label instead of falling back to any link targeting `/`.
• Ran `php php-transformer/tests/contract/run.php`; it passed.

How to test

1. Run cd php-transformer && composer install --no-interaction --prefer-dist --no-progress && composer test; expect passes as recorded by Cook's deterministic gate.

Compatibility

Fragment-only links no longer name the front page; hash-less home links continue to be used. Existing title fallbacks handle cases without an eligible link.

Evidence

• Verified command cd php-transformer && composer install --no-interaction --prefer-dist --no-progress && composer test: status=succeeded; candidate commit eeb471474374d36de1840b096e5c2effb0cf3762, tree e5b0ccf98a1c7a7753e6c715f3de8b23c3fc90b2, fingerprint 61c1cf0ba62f101f147419f1beab0c756a01c0a514156dc8ce81d786c8b80ace; durable gate gate-1
• Base unchanged since verification: trunk remains at 354dfdf.
• CI expected: Homeboy CI after push
• Candidate adoption provenance: the candidate was promoted from the recorded Cook task execution.
• Cook deterministic verification: 1 gate(s) completed green.
• Durable run execution: Succeeded
• Reviewer-resolvable evidence from source_refs[0]: Front page is named after a same-page fragment nav link ("Area of Focus expand_more") #3041
• Task objective: Front page is named after a same-page fragment nav link ("Area of Focus expand_more") #3041
• Verified candidate scope: 1 changed file(s): php-transformer/src/ArtifactCompiler/ArtifactCompiler.php.
• Verified finalization base: trunk at 354dfdf
• deterministic gate passed: sh -c cd php-transformer && composer install --no-interaction --prefer-dist --no-progress && composer test (Passed)

AI assistance

• AI assistance: Yes
• Tool(s): Homeboy (pi)
• Model: subagent
• Used for: Fixes issue Front page is named after a same-page fragment nav link ("Area of Focus expand_more") #3041, where a same-page fragment navigation label could incorrectly become the front-page title.