chore: consolidate runtime data layout under single data/ root directory

Migrate all runtime artifacts (database, uploads, VAPID keys, locks, bot state, container workspaces, zip staging) from scattered locations (`var/`, `devplacepy/static/uploads/`) into a unified `data/` directory. Update `config.py` as single source of truth with `DATA_PATHS` registry and `ensure_data_dirs()`, add `devplace migrate-data` CLI command with CRC verification and idempotent relocation, adjust `.dockerignore`, `.env.example`, `.gitignore`, `Dockerfile`, `Makefile`, `README.md`, `AGENTS.md`, `CLAUDE.md`, and all import paths in `attachments.py` to reference `config.UPLOADS_DIR`/`ATTACHMENTS_DIR` instead of computing from `STATIC_DIR`.

devplacepy/services/bot/config.py

@@ -1,9 +1,8 @@
 # retoor <retoor@molodetz.nl>
 
 import random
-from pathlib import Path
 
-from devplacepy.config import INTERNAL_GATEWAY_URL, INTERNAL_MODEL
+from devplacepy.config import INTERNAL_GATEWAY_URL, INTERNAL_MODEL, BOT_DIR
 
 BASE_URL_DEFAULT = "https://pravda.education"
 API_URL_DEFAULT = INTERNAL_GATEWAY_URL
@@ -15,8 +14,8 @@ OUTPUT_COST_PER_1M_DEFAULT = 1.10
 COST_WINDOW_SECONDS = 600
 COST_WARMUP_SECONDS = 120
 
-STATE_DIR = Path.home() / ".devplace_bots"
-ARTICLE_REGISTRY_PATH = Path.home() / ".dpbot_article_registry.json"
+STATE_DIR = BOT_DIR
+ARTICLE_REGISTRY_PATH = BOT_DIR / "article_registry.json"
 
 PROJECT_STATUSES = ["In Development", "Released"]