chore: remove unused code and suppress noisy Claude Code logs

- Delete unused files: retry.js, app-init.js, model-manager.js
- Remove duplicate error helpers from helpers.js (exist in errors.js)
- Remove unused exports from signature-cache.js, logger.js
- Remove unused frontend code: ErrorHandler methods, validators, canDelete, destroy
- Make internal functions private in thinking-utils.js
- Remove commented-out code from constants.js
- Remove deprecated .glass-panel CSS class
- Add silent handler for Claude Code event logging (/api/event_logging/batch)
- Suppress logging for /v1/messages/count_tokens (501 responses)
- Fix catch-all to use originalUrl (wildcard strips req.path)

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

public/js/components/model-manager.js

@@ -1,47 +0,0 @@
-/**
- * Model Manager Component
- * Handles model configuration (pinning, hiding, aliasing, mapping)
- * Registers itself to window.Components for Alpine.js to consume
- */
-window.Components = window.Components || {};
-
-window.Components.modelManager = () => ({
-    // Track which model is currently being edited (null = none)
-    editingModelId: null,
-
-    init() {
-        // Component is ready
-    },
-
-    /**
-     * Start editing a model's mapping
-     * @param {string} modelId - The model to edit
-     */
-    startEditing(modelId) {
-        this.editingModelId = modelId;
-    },
-
-    /**
-     * Stop editing
-     */
-    stopEditing() {
-        this.editingModelId = null;
-    },
-
-    /**
-     * Check if a model is being edited
-     * @param {string} modelId - The model to check
-     */
-    isEditing(modelId) {
-        return this.editingModelId === modelId;
-    },
-
-    /**
-     * Update model configuration (delegates to shared utility)
-     * @param {string} modelId - The model ID to update
-     * @param {object} configUpdates - Configuration updates (pinned, hidden, alias, mapping)
-     */
-    async updateModelConfig(modelId, configUpdates) {
-        return window.ModelConfigUtils.updateModelConfig(modelId, configUpdates);
-    }
-});