fix(talk): address remaining PR #741 reviewer feedback

Closes the seven outstanding items from the @claude review on PR #741:

1. Add empty `tests/client/talk/__init__.py` for pytest discovery parity
   with `tests/client/{collectives,news}/`.
2. Standardise boolean query params to integers — `includeStatus` was the
   string `"true"` in `list_conversations`/`list_participants` while every
   other flag (`noStatusUpdate`, `lookIntoFuture`, `setReadMarker`,
   `includeLastKnown`) used `1`/`0`.
3. Replace the `app:install || app:enable` chain in the spreed install hook
   with `app:install --keep-disabled --force || true; app:enable spreed`,
   so unrelated install failures surface as a clear "app not found" from
   `app:enable` rather than being silently masked.
4. Add `_validate_token()` (alphanumeric whitelist) and call it from all
   six TalkClient methods that interpolate the token into a URL path —
   defence-in-depth against pathological tokens reaching httpx.
5. Rename `TalkConversation.type` to `room_type` with `Field(alias="type")`
   and `populate_by_name=True`, so the field no longer shadows Python's
   builtin while preserving spreed's wire format on input. MCP responses
   now serialize `room_type` (field name) instead of `type`.
6. `mark_as_read` now passes `json=body or None` so the bodyless
   "mark everything as read" call doesn't send a spurious `{}` body and
   `Content-Type: application/json` header.
7. `_validate_message_text` rejects whitespace-only messages, not just
   empty strings.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

nextcloud_mcp_server/models/talk.py

@@ -2,7 +2,7 @@
 
 from typing import Any
 
-from pydantic import BaseModel, Field, field_validator
+from pydantic import BaseModel, ConfigDict, Field, field_validator
 
 from .base import BaseResponse, StatusResponse
 
@@ -48,9 +48,25 @@ class TalkConversation(BaseModel):
     flows.
     """
 
+    # ``populate_by_name=True`` lets us deserialize spreed's ``type`` key
+    # into the ``room_type`` field while still allowing internal callers
+    # to construct the model with ``room_type=...`` directly.
+    model_config = ConfigDict(populate_by_name=True)
+
     id: int
     token: str
-    type: int
+    # The spreed JSON wire format uses ``type`` for the room kind, but
+    # ``type`` shadows Python's builtin within the class scope, which
+    # would silently call this int field if anyone wrote ``type(...)``
+    # in a validator or method on this model. Map to ``room_type`` and
+    # alias the wire field instead.
+    room_type: int = Field(
+        alias="type",
+        description=(
+            "Conversation kind: 1=one-to-one, 2=group, 3=public, "
+            "4=changelog, 5=former one-to-one, 6=note-to-self."
+        ),
+    )
     name: str
     displayName: str
     description: str = ""