refactor(ai): strip Goose harness (Phase 1) — native/simple host-side only

Remove the Goose agentic harness across the codebase per
docs/spec-native-harness.md §3. Goose made N sequential model calls inside the
sandbox (slow on CPU-only hardware) and forced an in-container→host Ollama
gateway that tripped the rootless-Podman slirp4netns loopback bug.

- bridge.py: delete _run_goose/_goose_argv/_goose_present + GOOSE_* consts and
  the present-cache; __init__ now takes harness="simple"/max_turns=5; granted
  !task runs _run_simple until the native loop lands (Phase 2).
- __main__.py: --harness {native,simple} (was {goose,simple}); drop
  --goose-max-turns, add --max-turns; default harness simple.
- app.rs: /ai start accepts native|simple (plain aliases simple) instead of a
  bare plain flag; refresh harness comments.
- sbx.rs: remove the in-container Ollama gateway (Docker host-gateway / Podman
  slirp4netns host-loopback) and the dk_bootstrap OLLAMA_HOST env — kills the
  slirp4netns loopback bug; drop Goose comments.
- bootstrap.sh: drop goose from the prereq probe.
- bootstrap-ai.sh: remove the entire Goose install block, --no-goose flag,
  GOOSE_INSTALLER_URL, host config writer, and goose_bin helper.
- sandbox-bootstrap.sh: remove the in-sandbox Goose binary install + config.
- spec-goose-harness.md: banner — harness portion superseded; Podman stays.

cargo check + py_compile clean. No Goose refs remain (headroom/ untouched).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cmd_chat/agent/__main__.py

@@ -30,7 +30,7 @@ from __future__ import annotations
 import argparse
 import sys
 
-from .bridge import GOOSE_MAX_TURNS, AgentBridge
+from .bridge import AgentBridge
 from .profiles import load_profiles, provider_from_profile
 from .providers import OllamaEmbedder, make_provider, preflight
 
@@ -123,12 +123,12 @@ def main() -> None:
                     help="Ollama CPU threads (default: Ollama's own ≈ physical cores; benchmark 4/6/8)")
     ap.add_argument("--num-predict", type=int, default=None,
                     help="Ollama max reply tokens (default 512)")
-    ap.add_argument("--harness", choices=["goose", "simple"], default=None,
-                    help="sandbox !task harness: goose (agentic loop run inside the "
-                         "sandbox; default) or simple (legacy one-shot injector). "
-                         "Goose auto-degrades to simple if its binary isn't in the sandbox.")
-    ap.add_argument("--goose-max-turns", type=int, default=GOOSE_MAX_TURNS,
-                    help="max turns for a Goose agentic run (default %(default)s)")
+    ap.add_argument("--harness", choices=["native", "simple"], default=None,
+                    help="sandbox !task harness: native (bounded host-side Ollama "
+                         "tool-calling loop; default) or simple (one-shot injector). "
+                         "native degrades to simple if the model has no tool support.")
+    ap.add_argument("--max-turns", type=int, default=5,
+                    help="max turns for the native tool-calling loop (default %(default)s)")
     ap.add_argument("--system", default=None, help="override the system prompt")
     ap.add_argument("--context-window", type=int, default=12,
                     help="max prior messages fed to the model per reply")
@@ -201,8 +201,8 @@ def main() -> None:
         password=args.password, insecure=args.insecure, no_tls=args.no_tls,
         system_prompt=args.system, context_window=args.context_window,
         token_budget=args.token_budget, embedder=embedder, rag_top_k=args.rag_top_k,
-        code_provider=code_provider, harness=args.harness or "goose",
-        goose_max_turns=args.goose_max_turns,
+        code_provider=code_provider, harness=args.harness or "simple",
+        max_turns=args.max_turns,
     )
     try:
         bridge.run()