Add Aider provider with OpenRouter support and per-provider sidecar routing

- Add aider-runner.ts sidecar that spawns aider CLI in non-interactive mode
- Add Aider provider metadata with OpenRouter model presets
- Add aider-messages.ts adapter for Aider event format
- Refactor SidecarManager from single-process to per-provider process management
  with lazy startup on first query and session→provider routing
- Add openrouter_api_key to secrets system (keyring storage)
- Inject OPENROUTER_API_KEY from secrets into Aider agent environment
- Register Aider in provider registry, build pipeline, and resource bundle

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

v2/package.json

@@ -17,7 +17,7 @@
     "test:e2e": "wdio run tests/e2e/wdio.conf.js",
     "test:all": "bash scripts/test-all.sh",
     "test:all:e2e": "bash scripts/test-all.sh --e2e",
-    "build:sidecar": "esbuild sidecar/claude-runner.ts --bundle --platform=node --format=esm --outfile=sidecar/dist/claude-runner.mjs && esbuild sidecar/codex-runner.ts --bundle --platform=node --format=esm --outfile=sidecar/dist/codex-runner.mjs && esbuild sidecar/ollama-runner.ts --bundle --platform=node --format=esm --outfile=sidecar/dist/ollama-runner.mjs"
+    "build:sidecar": "esbuild sidecar/claude-runner.ts --bundle --platform=node --format=esm --outfile=sidecar/dist/claude-runner.mjs && esbuild sidecar/codex-runner.ts --bundle --platform=node --format=esm --outfile=sidecar/dist/codex-runner.mjs && esbuild sidecar/ollama-runner.ts --bundle --platform=node --format=esm --outfile=sidecar/dist/ollama-runner.mjs && esbuild sidecar/aider-runner.ts --bundle --platform=node --format=esm --outfile=sidecar/dist/aider-runner.mjs"
   },
   "devDependencies": {
     "@sveltejs/vite-plugin-svelte": "^6.2.1",