test: guard canonical LENS alias nodes

[MarcoPorcellato]

Description

Fixes #92

Adds the missing graph-aware LENS regression for a page P whose alias is Alt and whose content links to [[Alt]]. The final NetworkX node set must remain exactly {"P"}; no duplicate Alt page node is allowed.

This PR is test-only. The released production behavior already resolves the alias to the canonical page title, so no parser, graph, LENS implementation, documentation, or changelog change is needed.

Type of change

• 🐛 Bug fix (non-breaking regression coverage)
• ✨ New feature
• 💥 Breaking change
• 📚 Documentation update

Verification

• Historical mutation RED: replacing graph-aware title resolution with the literal reference produced {"P", "Alt"} and failed the new assertion.
• Current implementation GREEN: the dedicated regression passed.
• Focused LENS/alias suite: 12 passed, 47 deselected.
• Full quality gate: 762 passed, total coverage 91.20%.
• Package contract: wheel contract passed; Twine 6.2.0 accepted both wheel and sdist.
• Final diff: one test file, 18 added lines, no production change.

🛡️ Sovereign Developer Checklist

• I have read the contribution guidance.
• I have executed make all locally, and all linters, type-checkers, documentation checks, and tests pass.
• I have added the focused regression test.
• Documentation is unchanged because this PR only records already documented and released behavior.
• No changelog entry is needed because there is no user-visible behavior change.
• The test follows the project's typing conventions.

🤖 AI assistance and data handling

• AI assistance was used; the maintainer reviewed the complete diff and remains responsible for it.
• No private vault data, credentials, tokens, or unpublished security details were uploaded.
• The complete diff follows the AI-assisted contribution policy.

🧭 Contract impact

• No documented API or runtime contract changes.
• This PR makes no unsupported external or release-provenance claim.

Screenshots / CLI Output

Not applicable.