Fix HighMemoryUsage alert ratio validation

[shihuajin111]

Summary

Fixes the recommended HighMemoryUsage Prometheus alert so it no longer divides process_resident_memory_bytes by itself. The alert now compares resident process memory to machine_memory_bytes, matching the existing memory usage recording rule in this monitoring setup.

Fixes #1.

Changes

• Replaced the self-dividing HighMemoryUsage expression with process_resident_memory_bytes / machine_memory_bytes > 0.9.
• Added alert rule validation that catches missing expressions and exact self-dividing PromQL series expressions.
• Runs validation before alert rule upload, including dry-run mode.
• Wires validation failures through CLI exit codes by returning upload failures from --alerts / --init and calling sys.exit(main()).

Testing

• python3 -m py_compile tools/monitoring_setup.py - passed.
• python3 tools/monitoring_setup.py --alerts --dry-run - passed; dry-run output now includes expr: process_resident_memory_bytes / machine_memory_bytes > 0.9.
• File-level validation check confirmed validate_alert_rules(RECOMMENDED_ALERT_RULES) returns [].
• File-level validation check confirmed validate_alert_rules([{"name": "BadMemory", "expr": "process_resident_memory_bytes / process_resident_memory_bytes > 0.9"}]) reports the self-dividing expression.
• python3 tools/monitoring_setup.py --validate --prometheus-url http://127.0.0.1:1 --alertmanager-url http://127.0.0.1:1 prints recommended alert rules: OK and exits 1 only because no local Prometheus/Alertmanager is listening on that test port.
• python3 build.py was attempted on Windows. It did not reach the diagnostic finalization step because build.py launches frontend npm install as subprocess.run(["npm", ...]); on this Windows environment Node provides npm.cmd, which shutil.which("npm") finds but subprocess.run(["npm", ...]) cannot execute directly.
• python3 build.py -m backend was run to generate diagnostic artifacts. It exits 1 because Rust/Cargo is not installed in this environment, and it generated:
  • diagnostic/build-2b54872c.logd
  • diagnostic/build-2b54872c.json

Checklist

• Relevant modules affected by these changes build locally
• Tests pass locally
• Diagnostic build log is committed in this PR
• Documentation has been updated, if applicable
• Configuration or schema changes are documented, if applicable
• No generated build artifacts are committed, except the required diagnostic build log
• Changes are scoped to the PR purpose and avoid unrelated cleanup
• Security, privacy, and error-handling implications have been considered

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• I would like to request that my diagnostic build log is removed before merging