feat: Add database table for model context length configuration (#477)

* feat: add database table for model context length configuration

- Add model_context table with provider/model/context_limit fields
- Implement UPSERT endpoint for model context configuration
- Add priority lookup: database > config.yaml > custom_providers > cache
- Add frontend click-to-edit UI in ChatInput with tooltip
- Add i18n support for context editing dialog (all 8 locales)
- Use context_limit field consistently across frontend and backend

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix: use useMessage() composable instead of window.$message in ChatInput

- Remove incorrect NMessage import (not a component)
- Use useMessage() composable from naive-ui
- Replace window.$message?.xxx() with message.xxx()
- Fixes TypeScript build errors

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/server/src/db/hermes/schemas.ts

@@ -89,6 +89,21 @@ export const COMPRESSION_SNAPSHOT_SCHEMA: Record<string, string> = {
   updated_at: 'INTEGER NOT NULL',
 }
 
+// ============================================================================
+// Model Context (model-context.ts)
+// ============================================================================
+
+export const MODEL_CONTEXT_TABLE = 'model_context'
+
+export const MODEL_CONTEXT_SCHEMA: Record<string, string> = {
+  id: 'INTEGER PRIMARY KEY AUTOINCREMENT',
+  provider: 'TEXT NOT NULL',
+  model: 'TEXT NOT NULL',
+  context_limit: 'INTEGER NOT NULL',
+}
+
+export const MODEL_CONTEXT_INDEX = 'CREATE UNIQUE INDEX IF NOT EXISTS idx_model_context_provider_model ON model_context(provider, model)'
+
 // ============================================================================
 // Group Chat (services/hermes/group-chat/index.ts)
 // ============================================================================
@@ -469,6 +484,13 @@ export function initAllHermesTables(retryCount = 0): void {
     // Compression snapshot
     syncTable(COMPRESSION_SNAPSHOT_TABLE, COMPRESSION_SNAPSHOT_SCHEMA)
 
+    // Model context
+    syncTable(MODEL_CONTEXT_TABLE, MODEL_CONTEXT_SCHEMA, {
+      indexes: {
+        idx_model_context_provider_model: MODEL_CONTEXT_INDEX,
+      }
+    })
+
     // Group chat - basic tables
     syncTable(GC_ROOMS_TABLE, GC_ROOMS_SCHEMA)
     syncTable(GC_MESSAGES_TABLE, GC_MESSAGES_SCHEMA)