Move the Global module from packages/opencode/src/global to packages/core/src/global
to provide a unified location for managing XDG directories and application paths.
This eliminates duplicate path definitions across packages and ensures consistent
access to data, config, cache, state, log, and bin directories throughout the codebase.
Moves effect logging, observability, runtime utilities, flags, installation
version info, and process utilities from opencode to core package. This
enables better code sharing across packages and establishes core as the
single source of truth for foundational utilities.
All internal imports updated to use @opencode-ai/core paths for consistency.
Extract error handling, parsing logic, and variable substitution into dedicated
modules. This reduces duplication between tui.json and opencode.json parsing
and makes the config system easier to extend for future config formats.
Fixes potential plugin resolution issues when switching between projects by wrapping
plugin loading in Instance.provide(). This ensures each plugin resolves dependencies
relative to its correct project directory instead of inheriting context from whatever
instance happened to be active.
Also reorganizes config loading code into focused modules (command.ts, managed.ts,
plugin.ts) to make the codebase easier to maintain and test.
