feat: complete Run 91 effort instance identity

[try-works]

Summary

Completes Run 91 reasoning-effort instance identity across routing, persistence, Pi 0.84.2 discovery, provider/UI projections, variant-local role eligibility, benchmark and observed-performance attribution, and end-to-end extension lineage.

Also includes two delivery-gate repairs:

• deterministic Pi publication testing (no unintended taxonomy network fallback), and
• idempotent runtime UI validation when its exact endpoint already exists in the retained validation state.

TDD and regression coverage

• RED: Pi publication test timed out because startup used the fallback runtime taxonomy fetch.
• GREEN: injected the deterministic taxonomy fixture; the focused test now passes in 26 ms and the full Pi suite passes 100/100.
• RED: a second runRuntimeUiValidation() call against the same state root failed with Endpoint effort slot ... is already active.
• GREEN: validator recognizes only that exact parsed duplicate-activation response; retained-state regression passes.

Real behavior proof

Setup: Windows 11, Node 24.11.0, pnpm 10 via Corepack.

Commands run on this merged branch:

corepack pnpm run ci:check
corepack pnpm --filter @try-works/pi-role-model test
corepack pnpm run runtime:test-critical
corepack pnpm run runtime:validate-ui
corepack pnpm run runtime:validate-observability
corepack pnpm run test:rust
corepack pnpm run smoke

After-fix evidence:

• full workspace gate completed its lint/schema/build/test portion with 84 test files passed, 753 tests passed, 3 expected skips; it then revealed the Pi timeout that this PR fixes;
• rerun Pi suite: 16 files / 100 tests passed;
• retained-state UI validation regression passed;
• standalone UI validation passed after the fix, including account upsert, endpoint activation/readback, routed telemetry, mixed alias resolution, and router-decision consistency;
• observability validation, Rust tests, and gateway smoke passed.

Not tested here: a new cloud deployment or production promotion; Run 91 Phase 5 has its separate rebuilt-runtime and Pi end-to-end evidence binder in the paired private run artifacts.