refactor: run-tool-runtime unification — ToolDefinition/ToolTarget split, Toolset as single boundary, prompt/resolver merge

refactor: skills module restructure — model/catalog/management/runtime/sources layers, single read entry, UsageSink contract

refactor: tools three-layer cleanup — ToolStack to runtime, execution_labels renamed, tests added

refactor: tools three-layer separation + run assembly/engine consolidation

refactor: task domain final convergence — admin→management, execution unified, delivery context homed

refactor: channel + task delivery consolidation — inbound pipeline split, unified delivery entry, legacy compat shell cleanup

refactor: tighten runtime/assembly/prompt boundaries + test coverage

refactor: runtime + session assembly + prompt wiring convergence

refactor: final tools convergence — catalog extraction, flat builtin dirs, tightened exports, test mirroring

refactor: remove builtin tool re-exports — use canonical builtin:: paths everywhere

refactor: run/engine + tools main path restructuring

refactor: session subsystem restructuring — core / runtime / store

refactor: run builder migration, Engine rename, ToolStackConfig simplification

refactor: Toolset runtime owner + session/run split + engine reorganization

refactor: tools system consolidation — directory, identity, toolset, exposure