fix(maintenance): write knowledge_type as NamedNode URI (not Literal)

[arshadansari27]

Hotfix on top of #83

The 2026-05-25 maintenance run on prod 0.1.112 normalized 62,176 ks:knowledgeType annotations BUT wrote them as Literal(\"http://knowledge.local/schema/fact\") rather than the canonical NamedNode(<.../schema/fact>) shape that the ingestion path produces (stores/triples.py:149).

Effect: /api/admin/stats/types now buckets the same logical type into two groups (URI form: ~80k rows, Literal form: ~62k rows). Total still 141,946 — no data lost — but the bifurcation maintenance was meant to fix moved sideways from CASING to TERM-TYPE.

# Verify on prod:
SELECT (COUNT(*) AS ?c) WHERE { ?b <ks:knowledgeType> ?v } FILTER(isLiteral(?v))
→ 62176   (the bad rows)
SELECT (COUNT(*) AS ?c) WHERE { ?b <ks:knowledgeType> ?v } FILTER(isIRI(?v))
→ 79770   (good URIs, original + already-lowercase)

Fix

_canonical_knowledge_type_uri strips the KS prefix if present, lowercases the suffix, applies the Relation→relationship alias, and rebuilds as NamedNode(KS + suffix). Handles three input shapes:

• NamedNode mixed-case (ks:Fact) — the original bifurcation
• Literal with full URI (the 62k bad rows from the broken run)
• Literal with bare name (\"Fact\") — defensive

After deploy, the next maintenance sweep on prod will repair the bad rows.

Tests

• test_uppercase_uri_lowered — original casing path
• test_already_lowercase_uri_is_no_op — idempotency
• test_relation_alias_to_relationship — alias collapse
• test_literal_with_full_uri_is_repaired — new: corrective pass for the 62k bad rows
• test_literal_bare_name_normalised_to_uri — defensive
• test_idempotent — convergence

701 tests pass, ruff clean.

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