feat: add detailed logging for module loading and context providers

Add INFO-level logging to help diagnose module loading issues:

- discovery.py: Log summary of discovered modules by tier (core/optional/internal)
- service.py: Log which modules are enabled for each platform (DEBUG level)
- page_context.py: Log context building with platform info and which
  modules contributed context with key counts

Example log output:
  [MODULES] Auto-discovered 18 modules: 5 core, 11 optional, 2 internal
  [CONTEXT] Building PLATFORM context for platform 'main' with 5 enabled modules
  [CONTEXT] Context providers called: cms(3 keys), billing(3 keys)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/modules/core/utils/page_context.py

@@ -93,13 +93,24 @@ def get_context_for_frontend(
     # Determine which modules are enabled for this platform
     if platform:
         enabled_module_codes = module_service.get_enabled_module_codes(db, platform.id)
+        logger.info(
+            f"[CONTEXT] Building {frontend_type.value} context for platform "
+            f"'{platform.code}' with {len(enabled_module_codes)} enabled modules"
+        )
     else:
         # No platform context - only core modules
         enabled_module_codes = {
             code for code, module in MODULES.items() if module.is_core
         }
+        logger.info(
+            f"[CONTEXT] Building {frontend_type.value} context (no platform) with "
+            f"{len(enabled_module_codes)} core modules: {sorted(enabled_module_codes)}"
+        )
 
     # Collect context from enabled modules that have providers for this frontend
+    modules_with_providers = []
+    modules_contributed = []
+
     for code in enabled_module_codes:
         module = MODULES.get(code)
         if module is None:
@@ -108,15 +119,17 @@ def get_context_for_frontend(
         if not module.has_context_provider(frontend_type):
             continue
 
+        modules_with_providers.append(code)
+
         try:
             contribution = module.get_context_contribution(
                 frontend_type, request, db, platform
             )
             if contribution:
                 context.update(contribution)
+                modules_contributed.append(f"{code}({len(contribution)} keys)")
                 logger.debug(
-                    f"[CONTEXT] Module '{code}' contributed {len(contribution)} keys "
-                    f"for {frontend_type.value}"
+                    f"[CONTEXT] Module '{code}' contributed: {list(contribution.keys())}"
                 )
         except Exception as e:
             logger.warning(
@@ -124,6 +137,15 @@ def get_context_for_frontend(
                 f"{frontend_type.value}: {e}"
             )
 
+    if modules_contributed:
+        logger.info(
+            f"[CONTEXT] Context providers called: {', '.join(modules_contributed)}"
+        )
+    elif modules_with_providers:
+        logger.info(
+            f"[CONTEXT] {len(modules_with_providers)} modules have providers but none contributed"
+        )
+
     # Add any extra context passed by the caller
     if extra_context:
         context.update(extra_context)