feat: add default permission mode + rename accept→edit

- Add "default" permission mode: no flags passed to CC, uses its own
  built-in default (asks about everything). Now the system default.
- Rename "accept" alias to "edit" (acceptEdits) for clarity
- Remove "skip" alias (duplicate of "bypass")
- Update all help text, error messages, tests, and LLM prompts

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

agent/cc_runner.py

@@ -18,12 +18,13 @@ def strip_ansi(text: str) -> str:
 
 
 PERMISSION_MODE_FLAGS: dict[str, list[str]] = {
-    "bypassPermissions": ["--dangerously-skip-permissions"],
+    "default":           [],  # CC's own default: asks about everything
     "acceptEdits":       ["--permission-mode", "acceptEdits"],
     "plan":              ["--permission-mode", "plan"],
+    "bypassPermissions": ["--dangerously-skip-permissions"],
 }
 VALID_PERMISSION_MODES = list(PERMISSION_MODE_FLAGS)
-DEFAULT_PERMISSION_MODE = "bypassPermissions"
+DEFAULT_PERMISSION_MODE = "default"
 
 
 async def run_claude(