fix(dashboard): make the NoAuth egress label map exhaustive + register 7 covering tests

[adivekar-utexas]

What

Two independent base-reds that were failing Fast Quality Gates on every open PR.

1. NoAuthAccountCard.tsx TS2345

EGRESS_LABEL_KEYS covered 4 of the 5 EffectiveEgressKind values, so own reached getEgressLabelKey:

Argument of type '"direct" | "own" | "inherited-proxy" | "pool-empty"'
is not assignable to parameter of type
'"direct" | "inherited-proxy" | "inherited-pool" | "pool-empty"'

The map is now typed Record<EffectiveEgressKind, string>, so it is exhaustive by construction: adding a kind without a label becomes a compile error instead of a latent TS2345. It gains an ownProxy label next to the existing four.

own is only ever built with a proxy attached, so the offending fallthrough is unreachable at runtime. The type gap was real though, and the gate correctly refused to widen its baseline for a new regression.

2. mutation-test-coverage --strict

7 covering unit tests were missing from stryker.conf.json tap.testFiles, so their mutant kills were not counting. Each is inserted at its sorted position. The gate now reports no drift.

Testing

• check:mutation-test-coverage --strict — no drift (was 10 gaps across 5 modules)
• check:docs-counts — soft-only, so nothing to fix there
• 29 tests across noauth-account-card and noauth-effective-egress pass
• 14 tests in dashboard-localization-contract pass
• ESLint clean on the changed file

I could not run check:dashboard-typecheck locally: tsc OOMs even under a 1 GB cap on this machine, so the type fix is verified by the targeted tests above and CI.

[adivekar-utexas]

Worth knowing before triage: this PR clears Fast Quality Gates for three other open PRs of mine (#14817, #14924, #14929), which all fail on the same two base-reds. Confirmed on this PR's run — Fast Quality Gates is green here and red there.

The Unit Tests fast-path 1-4 failures remain on every PR including this one. Those are broader upstream base-reds (MCP bundle on Node 24, a 512 MiB heap-budget test, OpencodeExecutor geo-rotation, bounded-read, GHE Copilot registry, and i18n zh-CN/zh-TW glossary), so I have deliberately left them alone rather than fold unrelated repairs into these PRs.