docs: refer to the MCP tools by their new underscore names

Update the README, MCP docs, in-app MCP page, i18n strings, landing copy,
docstrings and comments to match the renamed tools. CHANGELOG entries and
docs/plans are historical and left as they were.

backend/database/migrations.py

@@ -250,7 +250,7 @@ def _migrate_mcp_bindings(engine, inspector, tables: set[str]) -> None:
     """Drop the legacy ``default_intent`` column and add ``default_personality``.
 
     The intent tri-state (respond / rewrite / compose) has been collapsed
-    to a boolean: when true, ``voicebox.speak`` rewrites input through the
+    to a boolean: when true, ``voicebox_speak`` rewrites input through the
     profile's personality LLM before TTS.
     """
     if "mcp_client_bindings" not in tables:

backend/database/models.py

@@ -272,7 +272,7 @@ class MCPClientBinding(Base):
     label = Column(String, nullable=True)  # display name
     profile_id = Column(String, ForeignKey("profiles.id"), nullable=True)
     default_engine = Column(String, nullable=True)
-    # When true, voicebox.speak routes through the profile's personality LLM
+    # When true, voicebox_speak routes through the profile's personality LLM
     # (rewrite) before TTS by default. Callers can still override per call.
     default_personality = Column(Boolean, nullable=False, default=False)
     last_seen_at = Column(DateTime, nullable=True)