rebrand: rename VoiceBox to TalkBox throughout codebase

- All 'voicebox'/'Voicebox'/'VOICEBOX' strings replaced with 'talkbox'/'TalkBox'/'TALKBOX'
- Port changed from 17493 to 17494 (avoids conflict with upstream VoiceBox)
- MCP tool namespace: voicebox.* -> talkbox.*
- App bundle ID: sh.voicebox.app -> com.talkbox.app
- Binary names: voicebox-server -> talkbox-server, voicebox-mcp -> talkbox-mcp
- Docker user/group: voicebox -> talkbox
- Database: voicebox.db -> talkbox.db
- Env vars: VOICEBOX_* -> TALKBOX_*
- Asset files renamed: voicebox-logo.* -> talkbox-logo.*, etc.
- External binaries in tauri.conf.json updated to talkbox-server/talkbox-mcp

backend/database/migrations.py

@@ -1,6 +1,6 @@
-"""Column-level migrations for the voicebox SQLite database.
+"""Column-level migrations for the talkbox SQLite database.
 
-Why not Alembic?  voicebox is a single-user desktop app shipping as a
+Why not Alembic?  talkbox is a single-user desktop app shipping as a
 PyInstaller binary.  Every user has exactly one SQLite file.  Alembic's
 strengths -- migration tracking across environments, rollback, team
 coordination -- don't apply here and would add bundling complexity
@@ -249,7 +249,7 @@ 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, ``talkbox.speak`` rewrites input through the
     profile's personality LLM before TTS.
     """
     if "mcp_client_bindings" not in tables: