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>

BOT/tests/smoke_player_recap.py

@@ -12,9 +12,9 @@ import sys
 import tempfile
 from pathlib import Path
 
-_storage_env = os.environ.get("SREBOT_STORAGE_VOL_PATH", "").strip()
+_storage_env = os.environ.get("STORAGE_VOL_PATH", "").strip()
 if not _storage_env:
-    raise RuntimeError("SREBOT_STORAGE_VOL_PATH must be set")
+    raise RuntimeError("STORAGE_VOL_PATH must be set")
 STORAGE = Path(_storage_env)
 SEASON_START = "1772348400"
 SEASON_END   = "1777852799"