Stop the repo-ownership audit from flagging projected rationale nodes

[zzet]

What

Exempt KindRationale from the repo-prefix ownership audit, in both the in-memory classifier and the SQLite predicate that transcribes it.

Why

Every daemon start on a workspace holding repo-scoped development memories logged this at Error:

daemon: repo ownership is inconsistent — repo-scoped reads will silently return a subset
of the graph; the store holds both prefixed and unprefixed copies of the same code, or a
node's stamped repo differs from its id
  owned_code_nodes: 644746
  unowned_code_nodes: 0
  misprefixed_nodes: 9
  misprefixed_samples: ["rationale::mem3539475d73f80040", "rationale::mem4209e14e240d8045", …]

The graph was healthy. owned=644746 / unowned=0 means not mixed — no ghost population, which is the failure the detector exists for. Only misprefixed was non-zero, and every node in it was a false positive.

ClassifyNodePrefix already exempts the identity namespaces whose IDs deliberately do not mirror a source path: contracts, contract bridges, topics. projectMemories mints nodes of exactly that shape:

id := "rationale::" + e.ID
… FilePath: rationaleVirtualFile,   // ".gortex/rationale"
   RepoPrefix: e.RepoPrefix,        // stamped from the memory entry

A repo is stamped, but the identity is namespaced and the path is virtual, so strings.HasPrefix(n.ID, repoPrefix+"/") can never hold. KindRationale was simply never added to the exempt switch — so one repo-scoped memory was enough to drive Clean() false and escalate the whole audit to Error, with copy describing a data-loss bug that was not occurring.

index_health reported the same false positive, via repo_ownership.consistent: false plus the "Graph holds inconsistent repository ownership … untrack and re-track the repo" remediation.

Changes

• internal/graph/prefix_diagnostics.go — add KindRationale to the exempt switch in IsAuditableRepoSourceNode; explain why in the doc comment.
• internal/graph/store_sqlite/prefix_diagnostics.go — mirror it in auditableRepoSourceNodePredicate (kind NOT IN (…, 'rationale')). The file's contract is that the SQL is a transcription of the Go classifier and the two change together.
• internal/graph/prefix_diagnostics_test.go — classifier case for a projected rationale identity.
• internal/graph/storetest/storetest.go — projected rationale node in the cross-backend conformance fixture.

Only the ownership audit is affected. buildIndexHealthPayloadCtx's path-liveness probe also calls IsAuditableRepoSourcePath, but it walks NodesByKind(KindFile) only, so rationale nodes never reach it.

Verification

Both fences fail without their corresponding fix — confirmed by reverting each and re-running:

--- FAIL: TestClassifyNodePrefix/projected_rationale_identity_is_not_audited
        ClassifyNodePrefix() = "misprefixed_identity", want ""
--- FAIL: TestSQLiteStoreConformance/PrefixDiagnostics
        MisprefixedNodes = 2, want 1 (owned=1 unowned=1 misprefixed=2)

With the fix:

• go test -race ./internal/graph/ ./internal/graph/storetest/ — ok
• go test -race ./internal/graph/store_sqlite/ — ok (full suite, 1438s)
• golangci-lint run ./internal/graph/... — 0 issues