Reorg introduce api package containing Entry interface

[steiler]

Reorganizes the tree package by introducing a new pkg/tree/api surface and a pkg/tree/consts package, then updates the codebase to use those exported interfaces, types, and constants.

• Adds a dedicated API layer (pkg/tree/api) with Entry, LeafVariants, delete-path types, and non-revertive tracking; introduces pkg/tree/ops helpers (e.g., GetByOwner) and an ops interface.
• Moves tree constants to pkg/tree/consts and replaces many direct tree.RunningIntentName/RunningValuesPrio/Replace* usages with consts equivalents across datastore, targets, server, and tests.
• Refactors core tree implementation to use the new API types: method visibility changes (e.g., ShouldDelete, GetOrCreateChilds, ToJsonInternal), LeafVariants accessors, and TreeContext now exposing SchemaClient, ExplicitDeletes, and NonRevertiveInfo.
• Updates mocks and generated code to reflect new API package paths and added interface methods; adds a new mock for SdcpbPath.
• Adjusts update/path handling with SdcpbPath() and updates callers, plus broad test updates to match new APIs and constants.

[codecov]

Codecov Report

❌ Patch coverage is 46.25999% with 740 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pkg/utils/testhelper/testhelpers.go	0.00%	108 Missing ⚠️
pkg/tree/ops/validation/validate.go	61.38%	67 Missing and 11 partials ⚠️
pkg/tree/ops/treeexport.go	0.00%	58 Missing ⚠️
pkg/tree/api/childMap.go	31.14%	42 Missing ⚠️
pkg/tree/ops/getorcreatechilds.go	33.87%	37 Missing and 4 partials ⚠️
pkg/tree/ops/getdeletes.go	0.00%	35 Missing ⚠️
pkg/tree/api/choice_case_resolver.go	0.00%	33 Missing ⚠️
pkg/tree/ops/getdeviations.go	0.00%	29 Missing ⚠️
pkg/tree/ops/deletebranch.go	0.00%	28 Missing ⚠️
pkg/datastore/transaction_rpc.go	52.00%	22 Missing and 2 partials ⚠️
... and 48 more

📢 Thoughts on this report? Let us know!

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[faebr]

I really like the interface separation from the stateless ops. I always struggled to fully understand sharedEntryAttributes and this breaks it down! I assume the commented out functions in entry.go are the ones you will still implement right?

[faebr]

should the leaf_variants also be parts of the api / interface package or would it make sense to take this implementation into another package so to only have the interface definitions in the api package?