fix(skills-hub): fix dedup in browse_skills() programmatic API

browse_skills() is the TUI gateway's API for the web UI skills browser
(tui_gateway/server.py:6574). It had the same dedup-by-name bug as
do_browse() and unified_search() fixed in the parent commit: r.name is
not unique for browse-sh skills (Airbnb, Booking.com, Zillow all publish
"search-listings"), so the dedup loop silently dropped all but the first
skill with each task name.

Switch to r.identifier, which is always globally unique.

Add a regression test asserting that two browse-sh skills with the same
name but different hostnames both appear in the browse_skills() result.

hermes_cli/skills_hub.py

@@ -704,8 +704,8 @@ def browse_skills(page: int = 1, page_size: int = 20, source: str = "all") -> di
     seen: dict = {}
     for r in all_results:
         rank = _TRUST_RANK.get(r.trust_level, 0)
-        if r.name not in seen or rank > _TRUST_RANK.get(seen[r.name].trust_level, 0):
-            seen[r.name] = r
+        if r.identifier not in seen or rank > _TRUST_RANK.get(seen[r.identifier].trust_level, 0):
+            seen[r.identifier] = r
     deduped = list(seen.values())
     deduped.sort(key=lambda r: (-_TRUST_RANK.get(r.trust_level, 0), r.source != "official", r.name.lower()))
     total = len(deduped)