fix(health): suppress 404 when health monitor disabled + fix audit test assertion

- Sidebar.svelte: defer healthStore.refresh() until feature flags confirm
  health_monitor is enabled; skip entirely when disabled
- health.js: remove throw error from catch block — log and return null
  instead, preventing 'Uncaught (in promise)' on expected 404
- test_report_audit_immutability.py: fix mock assertions —
  audit_service uses logger.reason/reflect/explore, not logger.info
- HealthStore and Sidebar now produce zero network noise when
  FEATURES__HEALTH_MONITOR=false

backend/src/api/routes/git/_repo_operations_routes.py

@@ -293,14 +293,14 @@ async def generate_commit_message(
             history_objs = _gs.get_commit_history(dashboard_id, limit=5)
             history = [h.message for h in history_objs if hasattr(h, "message")]
 
-            from ...plugins.llm_analysis.models import LLMProviderType
-            from ...plugins.llm_analysis.service import LLMClient
-            from ...services.llm_prompt_templates import (
+            from src.plugins.llm_analysis.models import LLMProviderType
+            from src.plugins.llm_analysis.service import LLMClient
+            from src.services.llm_prompt_templates import (
                 DEFAULT_LLM_PROMPTS,
                 normalize_llm_settings,
                 resolve_bound_provider_id,
             )
-            from ...services.llm_provider import LLMProviderService
+            from src.services.llm_provider import LLMProviderService
 
             llm_service = LLMProviderService(db)
             providers = llm_service.get_all_providers()
@@ -325,7 +325,7 @@ async def generate_commit_message(
                 default_model=provider.default_model,
             )
 
-            from ...plugins.git.llm_extension import GitLLMExtension
+            from src.plugins.git.llm_extension import GitLLMExtension
 
             extension = GitLLMExtension(client)
             git_prompt = llm_settings["prompts"].get(