feat(llm): add Kilo Gateway provider support

[skulldogged]

Summary

This PR adds first-class support for Kilo Gateway across config, routing, API provider management, model catalog mapping, and the Settings UI.

Changes

• Added kilo_key and KILO_API_KEY support in config, with automatic provider registration as kilo (https://api.kilo.ai/api/gateway)
• Added routing defaults for Kilo:
  • channel / branch: kilo/anthropic/claude-sonnet-4.5
  • worker / compactor / cortex: kilo/anthropic/claude-haiku-4.5
• Added Kilo prefix handling (kilo/...) in provider routing helpers
• Added Kilo-specific OpenAI-compatible request handling to use /chat/completions (instead of /v1/chat/completions)
• Added compatibility headers for Kilo requests:
  • HTTP-Referer: https://github.com/spacedriveapp/spacebot
  • X-Title: spacebot
• Wired Kilo into provider APIs and model discovery (/api/providers, /api/models)
• Added Kilo to Settings provider list, model grouping, and icon mapping (using Kilo's official SVG mark)
• Updated docs/README to include Kilo in supported providers and config examples

Why

Kilo is OpenAI-compatible but uses a different chat completions path shape than providers that use /v1/chat/completions. This makes Kilo work out of the box in Spacebot with proper routing and setup support.

Note

Comprehensive integration of Kilo Gateway support with 14 files modified. Changes span config handling, provider routing (with Claude Sonnet 4.5 for channels and Claude Haiku 4.5 for workers), OpenAI-compatible API support with custom headers, model discovery endpoints, and UI components. Documentation updated across quickstart, config guide, and roadmap to reflect Kilo among supported providers (now 12 total).

_{Written by Tembo for commit 064b922. This will update automatically on new commits.}