Move provider adapters (anthropic, bedrock, azure), platform adapters
(telegram, slack, discord, feishu, dingtalk, matrix), and terminal backends
(modal, daytona) out of core into plugins/ workspace members. Core references
them via the plugin registries (get_provider_namespace / get_provider_service /
get_tool_provider / get_credential_pool_hook) instead of direct imports.
- Provider/platform/terminal adapters relocated under plugins/; pyproject
extras now reference workspace members, not inline dep specs.
- Anthropic credential discovery moved into a credential_pool_hook, including
the api_key_path_explicit OAuth-masquerade guard.
- Vercel AI Gateway + Vercel Sandbox removed (upstream deletion).
- Terminal backends resolve ModalEnvironment / DaytonaEnvironment lazily from
the plugin registry.
- uv.lock regenerated against the pluginified workspace (233 packages).
Verified: zero dead imports of relocated modules in core (import smoke test +
exhaustive rename-map grep); credential_pool test suite green.
ethernet