Driver v2: options struct literals become builders; drop MaxTime; ArrayFilters and Delete option changes

[TopherGopher]

Part of the easymongo refactor (see PLAN.md on the refactor branch).

Working context (read this first)

• Repository github.com/tophergopher/easymongo. Start from branch claude/mongotest-easymongo-refactor-wu2vhm; create a branch issue-<number>-<short-slug> from it and open a pull request back into it. PLAN.md on that branch is the source of truth; read it before writing code.
• Go project, single module, all packages at the repo root except the new easymongotest/ subpackage. The final toolchain target is Go 1.27 (set by Toolchain: go 1.27, latest dependencies, tidy, remove replace directives #10); any Go 1.24 or newer works until then. Before pushing: gofmt -l . prints nothing, go vet ./..., go test -race ./....
• The existing test suite (*_test.go at the root, package easymongo_test, every test function calling setup(t) from common_test.go) is the regression net for this refactor. It must pass after your change. It needs a Docker daemon reachable through the normal Docker environment and the mongo:8 image.
• Order matters. The driver package cannot compile half-migrated (the *mongo.Client type flows from Connection to Database to Collection), so the four driver issues Driver v2: migrate connect.go (mongo.Connect, Disconnect, BSONOptions, write concern) #2, Driver v2: options struct literals become builders; drop MaxTime; ArrayFilters and Delete option changes #3, Driver v2: primitive package merged into bson; replace x/bsonx in index.go #4 and Driver v2: Distinct returns a DistinctResult that must be decoded #5 land together in one pull request, worked in that order. Before them, New easymongotest subpackage wrapping mongotest/v2 #7 and Switch the easymongo test suite to easymongotest #8 must land so the test suite no longer depends on the old github.com/tophergopher/mongotest v0.1.0 module (which itself imports easymongo and breaks the moment easymongo's types change). Until mongotest's v2 module is tagged, use a local replace github.com/tophergopher/mongotest/v2 => ../mongotest/v2 in go.mod and say so in the pull request; Toolchain: go 1.27, latest dependencies, tidy, remove replace directives #10 removes it.
• Method is test-driven: write the tests listed under "Tests first", confirm they fail for the expected reason, then implement. Never delete, skip or weaken an existing test to get green; if a test must change because the public API changed (for example primitive.ObjectID to bson.ObjectID), change only the types.
• Driver v2 reference: https://pkg.go.dev/go.mongodb.org/mongo-driver/v2 and the migration guide https://github.com/mongodb/mongo-go-driver/blob/master/docs/migration-2.0.md. Signatures quoted in these issues were checked against v2.9.0.
• Do not add third-party dependencies unless this issue lists them.
• Tracking issue for the whole refactor: Tracking: easymongo refactor (mongo-driver v2, easymongotest helpers, toolchain) #13. The mongotest side is tracked in Tracking: mongotest refactor (stdlib Docker client, driver v1/v2 modules, lighter dependencies) mongotest#48.
• Commit messages: imperative summary line, blank line, body explaining why. Mention this issue number in the pull request description.

Why

Driver v2 collection methods take options.Lister[T] values. The &options.FindOptions{...} struct literals easymongo passes today no longer satisfy that interface. MaxTime fields were removed in favour of context deadlines, which easymongo already applies through Query.getContext() in query.go.

Scope

Convert each literal to a builder chain that only sets fields whose easymongo value is non-nil:

• find_query.go: FindOneOptions (99-114), FindOptions (140-166), CountOptions (182-191), DistinctOptions (206-209).
• aggregate.go: AggregateOptions (40-51).
• update_query.go: UpdateOptions (52-61). ArrayFilters changes from options.ArrayFilters to []any; update UpdateQuery.arrayFilters and its setter.
• delete_query.go: DeleteOptions (25-31) splits into DeleteOneOptions and DeleteManyOptions builders (options.DeleteOne(), options.DeleteMany()).
• find_and_query.go: FindOneAndUpdateOptions (127-141), FindOneAndReplaceOptions (147-160), FindOneAndDeleteOptions (191-201); ArrayFilters as above; options.ReturnDocument, options.Before, options.After are unchanged.
• Delete every MaxTime: assignment; confirm getContext() is applied to each of these calls so the timeout still takes effect.
• insert_query.go, replace_query.go, index.go, database.go already use constructors (options.InsertOne(), options.Replace(), options.CreateIndexes(), options.ListCollections().SetNameOnly(true), options.Collection()); verify they compile and that Index types still match.
• Keep the fluent easymongo API unchanged; this is an internal change.

Implementation details

options.Lister[T] is interface{ List() []func(*T) error }; every options.Find()-style builder satisfies it. Builder setters verified in v2.9.0 for FindOptionsBuilder: SetAllowDiskUse, SetAllowPartialResults, SetBatchSize(int32), SetCollation(*options.Collation), SetComment(any), SetHint(any), SetLimit(int64), SetProjection(any), SetSkip(int64), SetSort(any), SetNoCursorTimeout(bool). FindOne(), Count(), Distinct(), Aggregate(), UpdateOne(), UpdateMany(), DeleteOne(), DeleteMany(), FindOneAndUpdate(), FindOneAndReplace(), FindOneAndDelete() have the matching subsets. UpdateOptions.ArrayFilters is []any with SetArrayFilters([]any). Collection method shapes, for example: coll.Find(ctx, filter any, opts ...options.Lister[options.FindOptions]) (*mongo.Cursor, error), coll.DeleteOne(ctx, filter any, opts ...options.Lister[options.DeleteOneOptions]) (*mongo.DeleteResult, error).

Conversion pattern to apply everywhere (only set what the easymongo query has):

// before (v1)
opts := &options.FindOptions{Limit: q.limit, Skip: q.skip, Sort: q.sortFields, MaxTime: q.timeout}
// after (v2)
opts := options.Find()
if q.limit != nil { opts.SetLimit(*q.limit) }
if q.skip != nil  { opts.SetSkip(*q.skip) }
if len(q.sortFields) > 0 { opts.SetSort(q.sortFields) }
// MaxTime dropped: the ctx from q.getContext() already carries the deadline

Where easymongo stored *options.ArrayFilters, store []any and change the setter's parameter type to []any (or keep a ...any variadic for convenience).

For DeleteQuery, build options.DeleteOne() in One() and options.DeleteMany() in Many() from the same Collation/Hint fields.

Tests first

Existing tests for each file must pass unchanged. Add:

• A unit test per builder helper that a fully populated easymongo query yields the expected driver options (inspect the built options by applying the Lister to a zero struct).
• Timeout on a FindQuery still cancels a deliberately slow query ($where sleep or a large Limit on a big collection) with ErrTimeoutOccurred.
• Array filters: an update with ArrayFilters on a nested array succeeds (update_query_test.go).

Acceptance

• go vet ./... clean; no reference to MaxTime or options.ArrayFilters remains.

Depends on: #2. Lands in the same pull request as #2, #4 and #5.