feat/fix: Rich token usage popovers, robust LiteLLM context window bounds logic, and Skill management refactor

Refactor AI Config and Fix Login failure: Migrated services to a structured api directory, updated backend schemas for multiple TTS/STT providers, and improved settings/chat UI coverage.

fix: swarm control ui for empty sessions ...

- Ensures workspace_id is generated and persistently committed when opening Swarm Control without any nodes (or when reading legacy sessions)
- Fixes frontend Swarm Control layout to show File Explorer icons regardless of whether any nodes are actively attached
- Renders empty node file explorer properly linked to the single Hub backend session workspace for browser features to use

fix(frontend): swarm file explorer layout

refactor(frontend): move remaining pages into feature modules