fix(eve): avoid dev snapshot watcher subscriptions

[iroiro147]

Summary

• prevent Rolldown's dev watcher from subscribing to authored app source roots during eve dev
• disable Nitro config watching in dev because Eve's authored-source watcher owns rebuild/reload
• add scenario coverage for both dev watcher settings

Refs #570.

Tests

• pnpm --filter eve exec vitest run --config vitest.scenario.config.ts src/internal/nitro/host/create-application-nitro.scenario.test.ts
• pnpm --filter eve exec vitest run --config vitest.scenario.config.ts src/internal/nitro/host/dev-authored-source-watcher.scenario.test.ts src/internal/nitro/host/create-application-nitro.scenario.test.ts
• pnpm --filter eve exec vitest run --config vitest.unit.config.ts src/internal/nitro/host/start-development-server.test.ts
• pnpm exec oxfmt --check packages/eve/src/internal/nitro/host/create-application-nitro.ts packages/eve/src/internal/nitro/host/create-application-nitro.scenario.test.ts .changeset/dev-runtime-nitro-watchers.md
• pnpm exec oxlint packages/eve/src/internal/nitro/host/create-application-nitro.ts packages/eve/src/internal/nitro/host/create-application-nitro.scenario.test.ts
• git diff --check
• pnpm --filter eve run typecheck
• pnpm guard:invariants
• pnpm changeset status --since origin/main

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[iroiro147]

Rebased onto current main while preserving the newer mounted-extension and named-agent Nitro configuration. The patch still excludes app-root subscriptions from Rolldown and disables Nitro’s duplicate config watcher.\n\nValidated the full Nitro scenario file (18 tests), the eve package typecheck, invariant guard, and changed-file formatting.

[iroiro147]

Rebased onto latest main (74216c6). Resolved conflicts in create-application-nitro.ts and create-application-nitro.scenario.test.ts — took PR version, which replaces main's file-watcher subscription approach with polling-based snapshot refresh to avoid dev-mode watcher subscription overhead.