feat(vocero): add linked content and TALKFIRST greetings (#2)

Opening a report or podcast link now establishes an authenticated starting reference for the conversation. Users can select other accessible content or compare reports while retaining the original link, and TALKFIRST greetings can name the verified report or podcast.

Release notes:

- Added authenticated report and episode link resolution with bounded lookups and unavailable-content handling
- Added explicit conversation selection without restricting searches or changing the reference during comparisons
- Added contextual TALKFIRST greetings through both voice-proxy and HTTP reasoning paths
- Preserved backend permission checks, conversation isolation, cancellation, and the existing speech protocol

Reviewed-on: AquaPortal/s2s#2

vocero-api/vocero_api/services/conversations.py

@@ -11,6 +11,7 @@ from urllib.parse import urlsplit
 from starlette.requests import HTTPConnection
 
 from vocero_api.core import config as settings
+from vocero_api.models.content import ConversationContent
 from vocero_api.models.mcp import BackendLogin, CallerIdentity, IntegrationError, McpToolDefinition
 
 COOKIE_NAME = "vocero_browser"
@@ -24,6 +25,9 @@ class Conversation:
     backend_token: str = field(repr=False)
     profile: CallerIdentity
     expires_at: float
+    linked_content: ConversationContent = field(default_factory=ConversationContent)
+    current_content: ConversationContent = field(default_factory=ConversationContent)
+    greeting_pending: bool = False
     catalog: list[McpToolDefinition] = field(default_factory=list)
     history: list[list[dict[str, str]]] = field(default_factory=list, repr=False)
     generation: int = 0
@@ -49,6 +53,9 @@ class Conversation:
         self.backend_token = ""
         self.history.clear()
         self.catalog.clear()
+        self.linked_content = ConversationContent()
+        self.current_content = ConversationContent()
+        self.greeting_pending = False
 
 
 class ConversationStore:
@@ -60,7 +67,9 @@ class ConversationStore:
             if item.closed.is_set() or monotonic() >= item.expires_at:
                 self.remove(item.id)
 
-    def create(self, browser: str, login: BackendLogin) -> Conversation:
+    def create(
+        self, browser: str, login: BackendLogin, linked_content: ConversationContent | None = None
+    ) -> Conversation:
         self.prune()
         if len(self._items) >= settings.S2S_MAX_CONVERSATIONS:
             raise IntegrationError(503, "No hay capacidad para otra conversación. Intenta más tarde.")
@@ -70,6 +79,9 @@ class ConversationStore:
             backend_token=login.sessionToken.get_secret_value(),
             profile=login.user,
             expires_at=monotonic() + settings.S2S_CONVERSATION_TTL_SEC,
+            linked_content=linked_content or ConversationContent(),
+            current_content=linked_content or ConversationContent(),
+            greeting_pending=settings.S2S_START_SESSION_MODE == "TALKFIRST",
         )
         self._items[item.id] = item
         return item