refactor: make all scripts multi-project via env vars

Replace hardcoded harb references across the entire codebase:
- HARB_REPO_ROOT → PROJECT_REPO_ROOT (with deprecated alias)
- Derive PROJECT_NAME from CODEBERG_REPO slug
- Add PRIMARY_BRANCH (master/main), WOODPECKER_REPO_ID env vars
- Parameterize worktree prefixes, docker container names, branch refs
- Genericize agent prompts (gardener, factory supervisor)
- Update best-practices docs to use $-vars, prefix harb lessons

All project-specific values now flow from .env → lib/env.sh → scripts.
Backward-compatible: existing harb setups work without .env changes.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/ci-debug.sh

@@ -12,10 +12,9 @@ set -euo pipefail
 # Load shared environment
 source "$(dirname "$0")/../lib/env.sh"
 
-export WOODPECKER_SERVER="http://localhost:8000"
 # WOODPECKER_TOKEN loaded from .env via env.sh
-REPO="johba/harb"
-API="${WOODPECKER_SERVER}/api/repos/2"
+REPO="${CODEBERG_REPO}"
+API="${WOODPECKER_SERVER}/api/repos/${WOODPECKER_REPO_ID}"
 
 api() {
   curl -sf -H "Authorization: Bearer ${WOODPECKER_TOKEN}" "${API}/$1"