fix(openclaw-migration): case-preserving brand rewrite + one-time ~/.openclaw residue banner (#16327)

Two related fixes for OpenClaw-residue problems after an OpenClaw→Hermes
migration (especially migrations done via OpenClaw's own tool, which
doesn't archive the source directory).

1. optional-skills/migration/openclaw-migration/scripts/openclaw_to_hermes.py:
   rebrand_text() was rewriting ~/.openclaw/config.yaml → ~/.Hermes/config.yaml
   (capital H — a directory that doesn't exist). Now case-preserving:
   "OpenClaw" → "Hermes" (prose), but "openclaw" → "hermes" (so filesystem
   paths land on the real Hermes home). Regex logic unchanged — replacement
   function now checks if the matched text was all-lowercase and emits the
   replacement in the matching case.

2. agent/onboarding.py + cli.py: one-time startup banner the first time
   Hermes launches and finds ~/.openclaw/. Tells the user to run
   `hermes claw cleanup` to archive it, gated on the existing onboarding
   seen-flag framework (onboarding.seen.openclaw_residue_cleanup in
   config.yaml). Fires once per install; re-running requires wiping that
   flag or running cleanup directly.

Tests:
- 4 new TestDetectOpenclawResidue tests (present / absent / file-instead-
  of-dir / default-home smoke)
- 2 TestOpenclawResidueHint tests (content check)
- 2 TestOpenclawResidueSeenFlag tests (flag isolation + round-trip)
- test_rebrand_text_preserves_filesystem_path_casing regression test
  with 4 scenarios including the exact ~/.openclaw/config.yaml case
- Existing test_rebrand_text_* tests updated to the new case-preserving
  contract (lowercase input → lowercase output)

Co-authored-by: teknium1 <teknium@noreply.github.com>

agent/onboarding.py

@@ -25,6 +25,7 @@ logger = logging.getLogger(__name__)
 
 BUSY_INPUT_FLAG = "busy_input_prompt"
 TOOL_PROGRESS_FLAG = "tool_progress_prompt"
+OPENCLAW_RESIDUE_FLAG = "openclaw_residue_cleanup"
 
 
 # -------------------------------------------------------------------------
@@ -94,6 +95,35 @@ def tool_progress_hint_cli() -> str:
     )
 
 
+def openclaw_residue_hint_cli() -> str:
+    """Banner shown the first time Hermes starts and finds ``~/.openclaw/``.
+
+    OpenClaw-era config, memory, and skill paths in ``~/.openclaw/`` will
+    otherwise attract the agent (memory entries like ``~/.openclaw/config.yaml``
+    get carried forward and the agent dutifully reads them). ``hermes claw
+    cleanup`` renames the directory so the agent stops finding it.
+    """
+    return (
+        "Heads up — an OpenClaw workspace was detected at ~/.openclaw/.\n"
+        "After migrating, the agent can still get confused and read that "
+        "directory's config/memory instead of Hermes's.\n"
+        "Run `hermes claw cleanup` to archive it (rename → .openclaw.pre-migration). "
+        "This tip only shows once; rerun it any time with `hermes claw cleanup`."
+    )
+
+
+def detect_openclaw_residue(home: Optional[Path] = None) -> bool:
+    """Return True if an OpenClaw workspace directory is present in ``$HOME``.
+
+    Pure filesystem check — no side effects. ``home`` override exists for tests.
+    """
+    base = home or Path.home()
+    try:
+        return (base / ".openclaw").is_dir()
+    except OSError:
+        return False
+
+
 # -------------------------------------------------------------------------
 # State read / write
 # -------------------------------------------------------------------------
@@ -149,10 +179,13 @@ def mark_seen(config_path: Path, flag: str) -> bool:
 __all__ = [
     "BUSY_INPUT_FLAG",
     "TOOL_PROGRESS_FLAG",
+    "OPENCLAW_RESIDUE_FLAG",
     "busy_input_hint_gateway",
     "busy_input_hint_cli",
     "tool_progress_hint_gateway",
     "tool_progress_hint_cli",
+    "openclaw_residue_hint_cli",
+    "detect_openclaw_residue",
     "is_seen",
     "mark_seen",
 ]