refactor(effect): unify service namespaces and align naming

[kitlangton]

Summary

Unifies all Effect service namespaces to follow the patterns in EFFECT_MIGRATION_PLAN.md.

Fully-migrated modules (single namespace, no suffix)

Collapse the two-namespace pattern (Foo + FooService class) into a single domain namespace with Interface, Service, layer, defaultLayer, and facade functions:

• File, FileTime, FileWatcher, Format, Vcs, Skill, Snapshot, Discovery

Mixed-mode modules collapsed into index

These had separate effect.ts + index.ts files. Since they go through instances.ts (lazy via LayerMap), there's no circular import — collapsed into one file:

• Question — question/service.ts deleted, everything in question/index.ts
• PermissionNext — permission/service.ts deleted, everything in permission/index.ts
• ProviderAuth — provider/auth-service.ts deleted, everything in provider/auth.ts

Mixed-mode modules kept separate (eager runtime import)

These are imported eagerly by runtime.ts for ManagedRuntime.make, so they can't be collapsed without circular deps:

• AccountEffect — account/service.ts → account/effect.ts
• AuthEffect — auth/service.ts → auth/effect.ts

Other changes

• AuthServiceError → AuthError
• DiscoveryService → Discovery
• ProviderAuth.methods() return type narrowed to Record<ProviderID, Method[]> with ProviderID.make() at the plugin boundary
• Removed remeda dependency from provider/auth.ts (replaced with Effect Array.filterMap)
• Bus subscriptions in Vcs and Format converted to Effect.acquireRelease
• Removed no-op init() methods and unnecessary defaultLayer = layer aliases
• All Effect.fn trace names use bare domain ("File.read", "Permission.ask")
• All interfaces named Interface consistently
• Fixed sortHiddenLast double hidden() call
• Fixed Snapshot revert to use first patch hash for overlapping files (was using last due to Map overwrite)
• Fixed Windows CI: dispose instances before temp dir cleanup in project-init-git test

Test plan

• tsc --noEmit passes
• bun turbo typecheck passes across all packages
• 135 tests pass across 7 changed test files
• New test: snapshot revert with overlapping patches
• Full local test suite: 1336 pass (5 pre-existing flaky failures in FileWatcher/Session unrelated to this PR)

[kitlangton]

CI status: Linux unit tests pass. Windows unit test failure is pre-existing on dev (last 4 dev test runs all fail on Windows). The Windows error is an unhandled ENOENT from ripgrep.ts:238 between test files — a background file indexing race that exists independent of this PR.