Refactor to prometheus_client, JSON logging, and codebase cleanup

- Replace file-based metrics and HTTP server with prometheus_client
  (Gauge + start_http_server), eliminating file I/O race conditions
- Fix ThreadProbe and thread restart lambda bugs
- Switch logging from RotatingFileHandler to JSON stdout for fluentd/Loki
- Add PYTHONUNBUFFERED=1 to Dockerfile for immediate container log output
- Upgrade base image from python:3.12.3-slim to python:3.13-slim
- Upgrade pyvmomi to 9.0.0.0; pin pydantic>=2.9.0 and typing_extensions>=4.12.2
  to use pre-built Python 3.13 wheels (removes Rust toolchain from build)
- Remove unused packages: boto3, botocore, s3transfer, jmespath, redis,
  docopt, pyflakes, posthog
- Remove unused imports (Posthog, CaseInsensitiveDict) and dead variables
  (callhomestats, local_site_info, lastStats)
- Fix service_profile() NameError (siteidentifier -> serviceProfileIdentifier)
- Remove bare print() in zvma.py __authhandler__, replace with self.log.info()
- Remove all commented-out PostHog blocks from zvma10/zvma.py
- Delete legacy zvma9_7/ module and app/logs/ directory
- Remove deprecated 'version: 3.3' from docker-compose.yml

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Dockerfile

@@ -1,11 +1,10 @@
-FROM python:3.12.3-slim
+FROM python:3.13-slim
 
 EXPOSE 9999
 
 # Install system dependencies
 RUN apt-get update \
     && apt-get install -y \
-    curl \
     gcc \
     libffi-dev \
     libssl-dev \
@@ -13,14 +12,12 @@ RUN apt-get update \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 
-# Install Rust and Cargo using curl with IPv4 only
-RUN CURL_IPRESOLVE=4 curl https://sh.rustup.rs -sSf | sh -s -- -y
-ENV PATH="/root/.cargo/bin:${PATH}"
-
 WORKDIR /usr/src/app
 
 # Set PYTHONPATH to include /usr/src/app
 ENV PYTHONPATH=/usr/src/app
+# Disable stdout buffering so logs appear immediately in the container console
+ENV PYTHONUNBUFFERED=1
 
 # Copy the zerto exporter into the container
 COPY app /usr/src/app/
@@ -29,8 +26,6 @@ COPY app /usr/src/app/
 RUN [ -f uuid.txt ] && rm uuid.txt || echo "No uuid.txt file to delete"
 
 # Install Python dependencies
-# Set environment variable for PyO3 compatibility
-ENV PYO3_USE_ABI3_FORWARD_COMPATIBILITY=1
 RUN pip install --upgrade pip
 RUN pip install --no-cache-dir -r requirements.txt