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/pi-test.sh

@@ -1,62 +0,0 @@
-#!/usr/bin/env bash
-set -euo pipefail
-
-SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-
-# Check for --no-env flag
-NO_ENV=false
-ARGS=()
-for arg in "$@"; do
-  if [[ "$arg" == "--no-env" ]]; then
-    NO_ENV=true
-  else
-    ARGS+=("$arg")
-  fi
-done
-
-if [[ "$NO_ENV" == "true" ]]; then
-  # Unset API keys (see packages/ai/src/env-api-keys.ts)
-  unset ANTHROPIC_API_KEY
-  unset ANTHROPIC_OAUTH_TOKEN
-  unset OPENAI_API_KEY
-  unset GEMINI_API_KEY
-  unset GROQ_API_KEY
-  unset CEREBRAS_API_KEY
-  unset XAI_API_KEY
-  unset OPENROUTER_API_KEY
-  unset ZAI_API_KEY
-  unset MISTRAL_API_KEY
-  unset MINIMAX_API_KEY
-  unset MINIMAX_CN_API_KEY
-  unset AI_GATEWAY_API_KEY
-  unset OPENCODE_API_KEY
-  unset COPILOT_GITHUB_TOKEN
-  unset GH_TOKEN
-  unset GITHUB_TOKEN
-  unset GOOGLE_APPLICATION_CREDENTIALS
-  unset GOOGLE_CLOUD_PROJECT
-  unset GCLOUD_PROJECT
-  unset GOOGLE_CLOUD_LOCATION
-  unset AWS_PROFILE
-  unset AWS_ACCESS_KEY_ID
-  unset AWS_SECRET_ACCESS_KEY
-  unset AWS_SESSION_TOKEN
-  unset AWS_REGION
-  unset AWS_DEFAULT_REGION
-  unset AWS_BEARER_TOKEN_BEDROCK
-  unset AWS_CONTAINER_CREDENTIALS_RELATIVE_URI
-  unset AWS_CONTAINER_CREDENTIALS_FULL_URI
-  unset AWS_WEB_IDENTITY_TOKEN_FILE
-  unset AZURE_OPENAI_API_KEY
-  unset AZURE_OPENAI_BASE_URL
-  unset AZURE_OPENAI_RESOURCE_NAME
-  echo "Running without API keys..."
-fi
-
-TSX_BIN="$SCRIPT_DIR/node_modules/.bin/tsx"
-if [[ ! -x "$TSX_BIN" ]]; then
-  echo "tsx not found at $TSX_BIN. Run npm install from the repo root first." >&2
-  exit 1
-fi
-
-"$TSX_BIN" "$SCRIPT_DIR/packages/coding-agent/src/cli.ts" ${ARGS[@]+"${ARGS[@]}"}