feat: replace Node.js bw CLI with native Rust binary + fix module name

Replace npm-based @bitwarden/cli with the pre-compiled native Rust bw
binary (v2026.7.0) to eliminate Node.js from the credential management
layer for CMMC/ITAR/STIG audit readiness.

Changes:
- Dockerfile: download native bw binary instead of npm install; add
  python3-pip for Playwright dependencies
- bw_helper.py: renamed from bw-helper.py (Python can't import hyphens);
  added BW_SERVER config for self-hosted instance; use --passwordfile
  for unlock (more reliable with native binary); removed TOTP from
  login flow (API key auth does not require it)
- provision-agent.py: pass BW_SERVER env var to BitwardenHelper
- docker-compose.yml: add BW_SERVER env var
- .env.example: add BW_SERVER, document TOTP as optional

Verified: dry-run passes, bw status/auth/generate all work inside
the provisioner container against pwvault.turnsys.com.

💘 Generated with Crush

Assisted-by: Crush:glm-5.2

docker-compose.yml

@@ -6,6 +6,7 @@ services:
       - BW_CLIENTID=${BW_CLIENTID}
       - BW_CLIENTSECRET=${BW_CLIENTSECRET}
       - BW_PASSWORD=${BW_PASSWORD}
+      - BW_SERVER=${BW_SERVER:-https://pwvault.turnsys.com}
       - BW_TOTP_SECRET=${BW_TOTP_SECRET:-}
       - HEADFUL=${HEADFUL:-false}
     volumes: