Toolchain: go 1.27, latest dependencies, tidy, remove replace directives

[TopherGopher]

Part of the easymongo refactor (see PLAN.md on the refactor branch). Last code step, after the driver migration is complete.

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.

Scope

• go 1.27 directive in go.mod.
• Dependencies at their latest releases: go.mongodb.org/mongo-driver/v2 (2.9.x or newer), github.com/stretchr/testify, github.com/tophergopher/mongotest/v2 at its first tagged release. Remove go.mongodb.org/mongo-driver (v1), docker.io/go-docker, github.com/gogo/protobuf, github.com/sirupsen/logrus, github.com/tophergopher/mongotest (v1 path).
• Delete both commented replace lines and any temporary replace ../mongotest/v2 used during development.
• go mod tidy; gofmt -l . and go vet ./... clean.
• Fix anything Go 1.27 vet flags (for example %w in Errorf inside the debug monitor at connect.go line 137 is passed to Errorf on the easymongo Logger, not fmt.Errorf, so it prints literally; switch to %v).
• Replace interface{} with any where touched (not a global rewrite).

Implementation details

Commands, in order, from the repo root:

go mod edit -go=1.27
go mod edit -dropreplace=github.com/tophergopher/mongotest/v2   # if the temporary replace is present
go get github.com/tophergopher/mongotest/v2@<tagged version> go.mongodb.org/mongo-driver/v2@latest github.com/stretchr/testify@latest
go mod edit -droprequire=go.mongodb.org/mongo-driver -droprequire=github.com/tophergopher/mongotest -droprequire=docker.io/go-docker -droprequire=github.com/gogo/protobuf -droprequire=github.com/sirupsen/logrus
GOTOOLCHAIN=go1.27.1 go mod tidy
gofmt -l . ; go vet ./... ; go test -race ./...

Then delete the two commented // replace lines by hand (go mod edit does not remove comments).

Acceptance

• go list -m all | wc -l is well below today's count (today's go.sum has 243 lines).
• No replace directive in go.mod.
• Full test suite green on Go 1.27.

Depends on: #2, #3, #4, #5, #6, #7, #8, #9 and the mongotest v2 module being tagged.