* fix(coding-agent): guard tree navigation during responses
* fix(coding-agent): simplify tree navigation regression
* fix(coding-agent): abort active run on session replacement and tree navigation
Session replacement (resume, new, fork, import) now settles the active
response in teardownCurrent before disposing the outgoing session, so the
aborted turn and its tool results persist instead of leaving a dangling
tool call. Tree navigation aborts the active response directly once the
user commits, without a confirmation gate.
Move provider auth and OAuth flows onto pi-ai Models, compose models.json and extension overlays through ModelRuntime, and retain ModelRegistry as an extension compatibility facade.
- treat tools as a global allowlist across built-in, extension, and SDK tools
- remove process-cwd singleton tool usage from SDK and CLI paths
- add regression coverage for extension tool filtering
closes#3452closes#2835
