feat: import logs from Google Cloud Logging

[STRRL]

Problem

Logs must be manually exported and uploaded (or piped via stdin) before LAPP can analyze them. There is no direct way to pull logs from Google Cloud Logging in either the CLI or the web UI.

Solution

Add a GCP log import path that fetches Cloud Logging entries via ADC and lands them as regular files in the workspace logs directory, so the existing discovery pipeline works unchanged. Web UI runs it as an async ImportRun job reusing the DiscoveryRun job pattern; CLI runs it synchronously.

Major Changes

• pkg/gcplog
  • New package: fetch Cloud Logging entries via logadmin API with ADC, render as timestamped text lines
• Import job model
  • New ImportRun record under import-runs/<id>/run.json with QUEUED/RUNNING/SUCCEEDED/FAILED states, progress, and startup recovery marking interrupted runs failed
• Web API and UI
  • New ImportLogs / GetImportRun / ListImportRuns RPCs (oneof source for future providers); import dialog with progress polling in the logs tab
• CLI
  • workspace add-log --gcp-project with --gcp-filter / --since / --limit, then the existing discovery flow