consolidate runtime env into .env, drop ecosystem env blocks (#1229)

- Make .env the single source of truth for runtime config. Remove all
  `env:` blocks from SREBOT/ecosystem.config.js and TSSBOT/ecosystem.config.js
  so values can't silently shadow .env. Both ecosystem files load .env via
  `require('dotenv').config()` and PM2 inherits the resolved environment.

- Rename SREBOT_STORAGE_VOL_PATH → STORAGE_VOL_PATH across all readers
  (BOT/utils.py, BOT/receiver_bridge.py, BOT/render_recap.py, server.js,
  web/server.js, dateindex.js, scripts/*, srebot.service, tests/, README,
  and both .env files). STORAGE is shared between SREBOT and TSSBOT, so the
  variable shouldn't carry one bot's prefix.

- Rename per-process PORT env vars to disambiguated names so .env can be
  the source of truth without collisions:
    PORT (api)     → SREBOT_API_PORT     (server.js)
    PORT (web)     → SREBOT_WEB_PORT     (web/server.js)
    WEBHOOK_PORT   → SREBOT_WEBHOOK_PORT (github_webhook_updater.py)
  SREBOT_EXTERNAL_HOST/PORT/UPSTREAM_URL were already uniquely named;
  they just move from ecosystem env to .env.

- TSSBOT/.env: drop GITHUB_WEBHOOK_SECRET (only srebot-webhook consumes it)
  and the stale SREBOT_DEPLOY_PATH. SREBOT/.env: also drop the obsolete
  SREBOT_DEPLOY_PATH (ecosystem now hardcodes __dirname).

- ecosystem.config.js no longer references SREBOT_DEPLOY_PATH; deploy path
  is always __dirname of the ecosystem file.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

dateindex.js

@@ -1,9 +1,9 @@
 require('dotenv').config();
 const sqlite3 = require('sqlite3').verbose();
 const path = require('path');
-const STORAGE_ROOT = (process.env.SREBOT_STORAGE_VOL_PATH || '').trim();
+const STORAGE_ROOT = (process.env.STORAGE_VOL_PATH || '').trim();
 if (!STORAGE_ROOT) {
-    throw new Error('SREBOT_STORAGE_VOL_PATH must be set');
+    throw new Error('STORAGE_VOL_PATH must be set');
 }
 const DB_PATH = path.join(STORAGE_ROOT, 'sq_battles.db');