feat: rework inmem resource state implementation

[smira]

This bring inmem closer to other state implementations:

• inmem.NewState() is now namespaced inside, not an instance per namespace
• one inmem state instance has a shared event buffer (stream) for all resource types and namespaces

This should provide better memory usage for any inmem user, and also it builds the foundation to build a shared, consistent watch API for the controller runtime (not in this PR).

[Copilot]

Pull request overview

This PR reworks the in-memory (inmem) state implementation to be a single shared state across namespaces/resource types, backed by a shared circular event buffer, bringing it closer to the behavior/shape of other state implementations and enabling more consistent watch semantics going forward.

Changes:

• Switch inmem.NewState() to return a single state instance (no longer per-namespace builders) and introduce a shared event buffer across all collections.
• Introduce new internal collection, eventbuffer, and errs packages to modularize storage/watch/error behavior.
• Update BoltDB backing store and tests to support the new “store is multi-namespace” BackingStore interface and simplify state setup across the repo.

Reviewed changes

Copilot reviewed 41 out of 43 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
pkg/state/wrap_test.go	Updates conformance test setup to use the new inmem.NewState() API.
pkg/state/teardowner_test.go	Updates teardown wrapper tests to use inmem.NewState() directly.
pkg/state/teardown_and_destroyer_test.go	Updates teardown+destroy wrapper tests to use inmem.NewState() directly.
pkg/state/registry/resource_test.go	Updates registry test setup to use inmem.NewState().
pkg/state/registry/namespace_test.go	Updates registry test setup to use inmem.NewState().
pkg/state/protobuf/protobuf_test.go	Updates protobuf state server/client tests to use inmem.NewState().
pkg/state/protobuf/client/client_test.go	Updates protobuf client test to use inmem.NewState().
pkg/state/owned/owned_test.go	Updates owned-state tests to use inmem.NewState().
pkg/state/impl/store/bolt/namespaced.go	Removes per-namespace Bolt backing store wrapper (no longer needed with multi-namespace store API).
pkg/state/impl/store/bolt/example_test.go	Updates example to show mixing persistent/ephemeral via namespaced.NewState, using a shared persistent inmem.State.
pkg/state/impl/store/bolt/conformance_test.go	Simplifies conformance setup by using a single inmem state with a multi-namespace Bolt backing store.
pkg/state/impl/store/bolt/bbolt.go	Refactors Bolt backing store to implement the updated multi-namespace inmem.BackingStore interface.
pkg/state/impl/store/bolt/bbolt_test.go	Updates Bolt backing store tests for multi-namespace load/put/destroy semantics.
pkg/state/impl/namespaced/namespaced_test.go	Updates namespaced state conformance to construct per-namespace core state via a factory that returns inmem.NewState().
pkg/state/impl/inmem/options.go	Updates history option docs and increases default shared buffer capacities for the new shared-buffer model.
pkg/state/impl/inmem/local_test.go	Updates tests for new constructors and adds coverage for shared history buffer behavior.
pkg/state/impl/inmem/internal/eventbuffer/export_test.go	Exposes watcher notify channel for testing feed isolation (test-only).
pkg/state/impl/inmem/internal/eventbuffer/eventbuffer.go	Introduces shared circular buffer + per-feed subscription model for watches.
pkg/state/impl/inmem/internal/eventbuffer/eventbuffer_test.go	Adds tests for feed isolation, overruns, bookmarks, tailing, and growth.
pkg/state/impl/inmem/internal/eventbuffer/bookmark.go	Introduces bookmark encoding/validation scoped to inmem runs.
pkg/state/impl/inmem/internal/errs/errs.go	Centralizes error types compatible with state error predicates.
pkg/state/impl/inmem/internal/collection/watch.go	Implements per-collection watch/watch-kind semantics using the shared event buffer.
pkg/state/impl/inmem/internal/collection/collection.go	Implements per-(namespace,type) collection storage and persistence hooks.
pkg/state/impl/inmem/internal/collection/collection_test.go	Adds comprehensive unit tests for collection CRUD, watch semantics, and persistence interactions.
pkg/state/impl/inmem/inmem.go	Reworks inmem state to be shared across namespaces/types and to use the new internal collection/eventbuffer packages.
pkg/state/impl/inmem/errors.go	Switches public inmem error helpers to the internal errs implementations.
pkg/state/impl/inmem/collection.go	Removes old monolithic per-type collection implementation (replaced by internal packages + shared buffer).
pkg/state/impl/inmem/build.go	Removes old builder helper tied to per-namespace construction.
pkg/state/impl/inmem/backing_store.go	Updates BackingStore interface to include namespace in Put/Destroy and Load callbacks.
pkg/state/impl/inmem/backing_store_test.go	Updates backing store mock/tests for new multi-namespace backing store API.
pkg/state/filter_test.go	Updates filter tests to use inmem.NewState() directly.
pkg/safe/state_test.go	Updates safe state tests to use inmem.NewState() directly.
pkg/resource/handle/handle_test.go	Updates handle tests to use inmem.NewState() directly.
pkg/controller/runtime/runtime_test.go	Updates controller runtime tests for new inmem API and shared-buffer option usage.
pkg/controller/generic/transform/transform_test.go	Updates transform controller tests to use inmem.NewState().
pkg/controller/generic/qtransform/qtransform_test.go	Updates qtransform controller tests to use inmem.NewState().
pkg/controller/generic/destroy/destroy_test.go	Updates destroy controller tests to use inmem.NewState().
pkg/controller/generic/cleanup/cleanup_test.go	Updates cleanup controller tests to use inmem.NewState().
Makefile	Regenerates Makefile and adds an image signing target/variable.
go.sum	Updates dependency checksums to match module version changes.
go.mod	Bumps a few module versions (e.g., grpc, compress, vtprotobuf).
cmd/runtime/main.go	Updates runtime main to use inmem.NewState() directly.
.gitignore	Regenerates .gitignore and adds additional ignored patterns.

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[Copilot]

Pull request overview

Copilot reviewed 47 out of 49 changed files in this pull request and generated no new comments.