fix(desktop+gateway): full multi-profile support over one global-remote dashboard (#39921)

* fix(desktop): cross-profile session history in app-global remote mode

#39894 made remote-profile sessions first-class for PER-PROFILE remote
overrides. But the common setup — Settings → Gateway → "All profiles" → Remote
— writes app-GLOBAL remote mode (connection.json top-level mode:'remote', empty
profiles map), which the intercept didn't recognize. Switching to a non-launch
profile then 404'd every session read, so no history showed for it.

In global remote mode a SINGLE backend serves every profile via ?profile= (it
reads each profile's state.db off the remote host's own disk — verified: one
dashboard returns /api/profiles and /api/profiles/sessions?profile=all across
all profiles). The fix: when no per-profile override matches but global remote
mode is active, route per-session reads/mutations to that one backend and KEEP
the ?profile= param so it opens the right state.db (instead of bailing to the
local path and dropping the profile scope).

- new globalRemoteActive() — true for connection.json mode:'remote' or the
  HERMES_DESKTOP_REMOTE_URL env override.
- per-session branch: per-profile override → route sans profile (own db);
  global mode → route to the single backend WITH ?profile= preserved.
- unified list is unchanged in global mode: it already passes through to the one
  backend, which aggregates all profiles natively.

Verified live against a one-dashboard / multi-profile remote (Austin's topology):
cross-profile transcript reads load (was 404), rename/delete route to the right
profile, unified list spans both profiles.

Known limitation (architectural, not fixed here): LIVE chat as a non-launch
profile still needs a per-profile dashboard on the remote — the dashboard binds
HERMES_HOME once at process start, so one global backend can't run an agent
turn as another profile. Session history/read/mutate now work regardless.

* fix(gateway): resume + chat any profile over one global-remote dashboard

The REST half of this branch made cross-profile session history visible in
app-global remote mode, but resume + chat still went over the WebSocket gateway,
which was hard-bound to the dashboard's launch profile. Resuming a non-launch
profile's session 404'd ("session not found") and sending spawned a new session
— because session.resume/prompt.submit had no profile concept and the live
agent + state.db were process-global to the launch profile's HERMES_HOME.

Make the WS gateway per-session profile-aware so ONE dashboard can serve every
local profile on its host (the app-global remote topology):

- session.resume accepts an optional `profile`. _profile_home() resolves that
  profile's home on this host; resume opens THAT profile's state.db, binds its
  HERMES_HOME (ContextVar override) while building the agent so config/skills/
  model resolve to it, and passes the profile db to the agent so turns persist
  to the right state.db. The owning profile_home is stored on the session.
- prompt.submit re-binds the stored profile_home for the turn thread (mid-turn
  home reads — memory, skills — resolve to the resumed profile), reset in finally.
- _make_agent gains an optional session_db param (defaults to _get_db()).
- _load_cfg honors the home override (falls back to _hermes_home) so a resumed
  profile loads its own config; cache keyed on resolved path.
- desktop: session.resume now sends the owning profile.

Omitted/launch profile → unchanged (single-profile and per-profile-remote setups
are byte-for-byte the same path). Verified live against a one-dashboard /
multi-profile remote: resuming a non-launch profile's session loads its history,
runs a real turn against THAT profile's home/env, and persists to its state.db.

tests/tui_gateway/test_protocol.py: _make_agent mocks updated for the new param.

tests/tui_gateway/test_protocol.py

@@ -315,7 +315,7 @@ def test_session_resume_returns_hydrated_messages(server, monkeypatch):
             ]
 
     monkeypatch.setattr(server, "_get_db", lambda: _DB())
-    monkeypatch.setattr(server, "_make_agent", lambda sid, key, session_id=None: object())
+    monkeypatch.setattr(server, "_make_agent", lambda sid, key, session_id=None, session_db=None: object())
     monkeypatch.setattr(server, "_init_session", lambda sid, key, agent, history, cols=80: None)
     monkeypatch.setattr(server, "_session_info", lambda _agent, _session=None: {"model": "test/model"})
 
@@ -366,7 +366,7 @@ def test_session_resume_handles_multimodal_list_content(server, monkeypatch):
             return [multimodal_user, text_only_assistant]
 
     monkeypatch.setattr(server, "_get_db", lambda: _DB())
-    monkeypatch.setattr(server, "_make_agent", lambda sid, key, session_id=None: object())
+    monkeypatch.setattr(server, "_make_agent", lambda sid, key, session_id=None, session_db=None: object())
     monkeypatch.setattr(server, "_init_session", lambda sid, key, agent, history, cols=80: None)
     monkeypatch.setattr(server, "_session_info", lambda _agent, _session=None: {"model": "test/model"})
 
@@ -432,7 +432,7 @@ def test_session_resume_reuses_existing_live_session(server, monkeypatch):
         def close(self):
             closed_sids.append(self.sid)
 
-    def make_agent(sid, key, session_id=None):
+    def make_agent(sid, key, session_id=None, session_db=None):
         created_sids.append(sid)
         first_agent_started.set()
         assert agent_can_finish.wait(timeout=1)
@@ -547,7 +547,7 @@ def test_session_resume_live_payload_uses_current_history_with_ancestors(server,
     monkeypatch.setattr(
         server,
         "_make_agent",
-        lambda _sid, key, session_id=None: types.SimpleNamespace(
+        lambda _sid, key, session_id=None, session_db=None: types.SimpleNamespace(
             model="test/model", session_id=session_id or key
         ),
     )
@@ -647,7 +647,7 @@ def test_session_branch_persists_branched_from_marker(server, monkeypatch):
     monkeypatch.setattr(
         server,
         "_make_agent",
-        lambda _sid, key, session_id=None: types.SimpleNamespace(
+        lambda _sid, key, session_id=None, session_db=None: types.SimpleNamespace(
             model="test/model", session_id=session_id or key
         ),
     )