chore: drop non-code junk (pi-mono-reference, runtime state, root duplicates)

Remove files that should never have been tracked:

- pi-mono-reference/: 688-file copy of an upstream monorepo, zero imports,
  used only as offline human reference
- build/electron-builder.runtime.json: environment-specific build artifact
  with hardcoded local paths
- state/cancel-signal-state.json: runtime state written by the app
- prompt.txt, logo.svg (root): exact duplicates of the canonical copies
  under .planning/archive/ and assets/

Add state/ to .gitignore so future runtime state stays out.

pi-mono-reference/test.sh

@@ -1,62 +0,0 @@
-#!/usr/bin/env bash
-set -e
-
-AUTH_FILE="$HOME/.pi/agent/auth.json"
-AUTH_BACKUP="$HOME/.pi/agent/auth.json.bak"
-
-# Restore auth.json on exit (success or failure)
-cleanup() {
-    if [[ -f "$AUTH_BACKUP" ]]; then
-        mv "$AUTH_BACKUP" "$AUTH_FILE"
-        echo "Restored auth.json"
-    fi
-}
-trap cleanup EXIT
-
-# Move auth.json out of the way
-if [[ -f "$AUTH_FILE" ]]; then
-    mv "$AUTH_FILE" "$AUTH_BACKUP"
-    echo "Moved auth.json to backup"
-fi
-
-# Skip local LLM tests (ollama, lmstudio)
-export PI_NO_LOCAL_LLM=1
-
-# Unset API keys (see packages/ai/src/stream.ts getEnvApiKey)
-unset ANTHROPIC_API_KEY
-unset ANTHROPIC_OAUTH_TOKEN
-unset OPENAI_API_KEY
-unset GEMINI_API_KEY
-unset GROQ_API_KEY
-unset CEREBRAS_API_KEY
-unset XAI_API_KEY
-unset OPENROUTER_API_KEY
-unset ZAI_API_KEY
-unset MISTRAL_API_KEY
-unset MINIMAX_API_KEY
-unset MINIMAX_CN_API_KEY
-unset KIMI_API_KEY
-unset HF_TOKEN
-unset AI_GATEWAY_API_KEY
-unset OPENCODE_API_KEY
-unset COPILOT_GITHUB_TOKEN
-unset GH_TOKEN
-unset GITHUB_TOKEN
-unset GOOGLE_APPLICATION_CREDENTIALS
-unset GOOGLE_CLOUD_PROJECT
-unset GCLOUD_PROJECT
-unset GOOGLE_CLOUD_LOCATION
-unset AWS_PROFILE
-unset AWS_ACCESS_KEY_ID
-unset AWS_SECRET_ACCESS_KEY
-unset AWS_SESSION_TOKEN
-unset AWS_REGION
-unset AWS_DEFAULT_REGION
-unset AWS_BEARER_TOKEN_BEDROCK
-unset AWS_CONTAINER_CREDENTIALS_RELATIVE_URI
-unset AWS_CONTAINER_CREDENTIALS_FULL_URI
-unset AWS_WEB_IDENTITY_TOKEN_FILE
-unset BEDROCK_EXTENSIVE_MODEL_TEST
-
-echo "Running tests without API keys..."
-npm test