fix(wiki): prevent concurrent duplicate page identities

[JYao-Chen]

Description

Wiki ingest allows concurrent batches for the same knowledge base and protects Reduce with per-slug locks. Two map workers can still extract the same same-type display title with different romanized slugs before either page exists. Because the reducers lock different slug keys, both pages can be created.

This change closes that window by:

• resolving an exact same-type, normalized-title candidate deterministically before the semantic dedup LLM call;
• reserving the chosen slug in Redis by (knowledge base, page type, normalized title) so concurrent batches converge before summaries and Reduce are materialized;
• using a batch-local claim in Lite mode and when Redis is unavailable;
• coalescing candidates that converge to one slug while preserving aliases, cited chunks, and the richer fallback text;
• keeping punctuation significant, so 寓言 and 《寓言》 remain distinct identities, and keeping entity/concept namespaces separate.

The claim is temporary and does not add a schema migration or change existing page data.

Type of Change

• 🐛 Bug fix
• ✨ New feature
• 💥 Breaking change
• 📚 Documentation update
• 🎨 Refactor
• ⚡ Performance improvement
• 🧪 Test
• 🔧 Configuration / Build / CI

Related Issue

No linked issue.

Testing

• go test ./internal/application/service -count=1
• go test -race ./internal/application/service -run TestWikiIdentityClaimConvergesDifferentSlugs -count=1
• go vet ./internal/application/service
• git diff --check origin/main...HEAD

The added regression tests cover concurrent workers proposing different slugs for the same title, authoritative existing-page resolution, Lite-mode batch convergence, entity/concept separation, punctuation-sensitive work titles, and evidence preservation during coalescing.

Checklist

• git diff --check origin/main...HEAD passes
• Changed source files are formatted
• Targeted tests for the changed packages/components pass
• Diff-scoped golangci-lint (not installed in the development environment)
• Full changed-package tests were run
• Self-reviewed the code
• Added/updated tests covering the change
• No documentation update required
• No breaking changes

Screenshots / Recordings

Not applicable; backend-only change.