feat: add session export with full and compressed modes (#507)

Add export functionality that allows users to download session data
as JSON or plain text, with optional LLM-based context compression
for long conversations. Includes UI controls in chat panel, session
list, and history view, plus i18n strings for all 8 locales.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

tests/server/sessions-routes.test.ts

@@ -17,6 +17,7 @@ const usageSingleMock = vi.fn(async (ctx: any) => { ctx.body = { input_tokens: 0
 const usageStatsMock = vi.fn(async (ctx: any) => { ctx.body = { total_input_tokens: 0, total_output_tokens: 0 } })
 const contextLengthMock = vi.fn(async (ctx: any) => { ctx.body = { context_length: 200000 } })
 const batchRemoveMock = vi.fn(async (ctx: any) => { ctx.body = { deleted: 1, failed: 0, errors: [] } })
+const exportSessionMock = vi.fn(async (ctx: any) => { ctx.body = JSON.stringify({ id: ctx.params.id }) })
 
 vi.mock('../../packages/server/src/controllers/hermes/sessions', () => ({
   listConversations: listConversationsMock,
@@ -36,6 +37,7 @@ vi.mock('../../packages/server/src/controllers/hermes/sessions', () => ({
   usageSingle: usageSingleMock,
   usageStats: usageStatsMock,
   contextLength: contextLengthMock,
+  exportSession: exportSessionMock,
 }))
 
 describe('session routes', () => {
@@ -66,6 +68,7 @@ describe('session routes', () => {
       '/api/hermes/usage/stats',
       '/api/hermes/sessions/context-length',
       '/api/hermes/sessions/:id',
+      '/api/hermes/sessions/:id/export',
       '/api/hermes/sessions/:id/usage',
       '/api/hermes/sessions/:id/rename',
     ]))
@@ -110,4 +113,15 @@ describe('session routes', () => {
     expect(getConversationMessagesMock).toHaveBeenCalledWith(detailCtx)
     expect(detailCtx.body).toEqual({ session_id: 'child-session', messages: [] })
   })
+
+  it('delegates session export to the controller', async () => {
+    const { sessionRoutes } = await import('../../packages/server/src/routes/hermes/sessions')
+    const layer = sessionRoutes.stack.find((entry: any) => entry.path === '/api/hermes/sessions/:id/export')
+    const handler = layer.stack[0]
+    const ctx: any = { params: { id: 'session-abc' }, query: {}, body: null, set: vi.fn() }
+
+    await handler(ctx)
+
+    expect(exportSessionMock).toHaveBeenCalledWith(ctx)
+  })
 })