Multiple identities via config subentries + regenerate + editable name

Refactor from one-entry-one-identity to a hub config entry (shared RNS stack)
plus config subentries of type "identity", each an independent LXMF identity
with its own LXMRouter, address, device and entities. This is required because
LXMRouter allows only one delivery identity per instance.

- ReticulumStack: owns the single process-wide RNS instance, peer discovery and
  interface telemetry (hub device).
- IdentityManager: one per subentry, its own LXMRouter/identity/destination and
  delivery callback (identity device). Signal handlers suppressed and atexit
  handlers tamed for each router too.
- Config subentry flow (add / reconfigure identity); a first identity is seeded
  on stack creation. Editable announce display name = subentry title.
- Per-identity "Regenerate identity" button: new address + re-announce
  (clears the router's single delivery destination first).
- Services and events gain an "identity" field to target/distinguish identities.
- Per-identity assist bridge, greeting-when-assist-off, allow-list, notify,
  announce/sync buttons, message counters; hub-level connectivity/telemetry/peers.

Verified against current HA config_entries/entity_platform/selector and RNS/LXMF
sources. Docs and en/ru translations updated.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

custom_components/reticulum/const.py

@@ -43,10 +43,18 @@ DEFAULT_LOGLEVEL: Final = 3  # RNS.LOG_NOTICE
 
 DELIVERY_METHODS: Final = ["direct", "opportunistic", "propagated"]
 
+# ---------------------------------------------------------------------------
+# Subentries
+# ---------------------------------------------------------------------------
+# The config entry is the shared Reticulum stack (RNS + TCP interface); each
+# LXMF identity is a config subentry of this type.
+SUBENTRY_TYPE_IDENTITY: Final = "identity"
+
 # ---------------------------------------------------------------------------
 # Storage
 # ---------------------------------------------------------------------------
 STORAGE_SUBDIR: Final = "reticulum"
+IDENTITIES_SUBDIR: Final = "identities"
 IDENTITY_FILENAME: Final = "identity"
 CONFIG_FILENAME: Final = "config"
 ATTACHMENTS_SUBDIR: Final = "attachments"
@@ -54,7 +62,19 @@ ATTACHMENTS_SUBDIR: Final = "attachments"
 # ---------------------------------------------------------------------------
 # Dispatcher signals
 # ---------------------------------------------------------------------------
-SIGNAL_STATE_UPDATED: Final = f"{DOMAIN}_state_updated"
+# Per-stack and per-identity update signals; suffix with entry_id / subentry_id.
+SIGNAL_STACK_PREFIX: Final = f"{DOMAIN}_stack"
+SIGNAL_IDENTITY_PREFIX: Final = f"{DOMAIN}_identity"
+
+
+def stack_signal(entry_id: str) -> str:
+    """Dispatcher signal for a stack (hub) state update."""
+    return f"{SIGNAL_STACK_PREFIX}_{entry_id}"
+
+
+def identity_signal(subentry_id: str) -> str:
+    """Dispatcher signal for an identity state update."""
+    return f"{SIGNAL_IDENTITY_PREFIX}_{subentry_id}"
 
 # ---------------------------------------------------------------------------
 # Events
@@ -79,6 +99,9 @@ ATTR_TITLE: Final = "title"
 ATTR_METHOD: Final = "method"
 ATTR_FIELDS: Final = "fields"
 ATTR_MAX_MESSAGES: Final = "max_messages"
+# Which identity a domain service should act through (title or LXMF address).
+# Omit to use the only/first identity.
+ATTR_IDENTITY: Final = "identity"
 
 # ---------------------------------------------------------------------------
 # LXMF address geometry