refactor(gateway): break /model, /new, /compress, /resume god methods into phase helpers
- slash_commands_model: _ModelSwitchContext dataclass replaces 12-kwarg plumbing; _handle_model_command (193 LOC) -> listing / switch / guard / commit phases; _commit_model_switch (175) -> cached-agent swap / record / confirmation; /fast and /reasoning display toggles routed through dict tables. - slash_commands_session: /new hooks + cleanup lifted; _handle_compress_command_inner -> _run_manual_compression; /resume -> resolve target / access-denied helpers; persisted-row ownership proof extracted (_persisted_row_proves_owner, _sattr). - Zero user-visible change (golden + differential fuzz vs base for guards, listing, /fast, /reasoning); test net 137 files / 1842 passed.
This commit is contained in: