fix(addie): enforce common fixed-trace tool universe

[bokelley]

Summary

• use an evaluator-owned, registry-derived candidate tool universe for routed/hybrid diagnostic generation
• reject absent, legacy, or forged common-universe provenance before provider or handler boundaries
• retain direct-arm non-admission and use synthetic receipt handlers only for component evaluation

Verification

• npm run typecheck
• focused fixed-trace tests (66 passing)
• npm run validate:addie-fixed-traces
• generated tool reference and inventory checks
• git diff --check

Implements an evaluation prerequisite for #6842 and #6846.

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Open workspace in Conductor

[aao-secretariat]

Ladon verdict: Approve

Approve — clean review, no blocking or medium findings.

This PR (fix(addie): enforce common fixed-trace tool universe) touches only Addie evaluation infrastructure under server/src/addie/** and server/tests/**. No protocol wire surface (static/schemas/source/**), normative reference docs, dist/** artifacts, or migrations are affected, so the changeset is correctly absent and no schema↔docs, oneOf, or artifact-immutability gates apply.

Verified points from the review:

• Removed FIXED_TRACE_DIRECT_TOOL_HANDLERS export was dead code with no consumers.
• Synthetic-receipt handler-identity fidelity and binding-sha invariant are fail-closed.
• Admission rejects absent/forged provenance before any provider dispatch or handler execution.

Decision-table walk: no critical/high (row 1 n/a); gated_paths is false (row 2 n/a); high_risk is true but all reasons are (modified) with NO medium finding, so rows 3–5 do not fire; no prior decision (row 6 n/a); no no-auto-approve team match (row 7 n/a); zero medium findings (row 8 n/a). Falls through to row 9 → approve. high_risk here is a heuristic signal on modified files with no reviewer concern, which is presumed safe.