fix(agent): chat console keeps its thread across turns and reloads (#1859)

Three user-reported failures in the assistant panel, one root cause each:

1. "The chat asks what I'm referring to" when continuing a thread. The
   single-call console (general.help, AskConsole -> /api/agent/ask) was
   stateless since the 08-20 model-agnostic cutover: conversationId was only
   the tool actor id, so every turn was answered blind, reload or not.
   The provider-agnostic GenerateTextRequest gains an optional `history`
   (real message turns before the prompt, in both the Anthropic-family and
   the OpenAI-compatible adapter; absent/empty leaves the request
   byte-identical to the single-turn call). The route loads the thread's
   earlier turns server-side (loadChatHistory: text only, hidden and tool
   rows dropped, alternation repaired, newest 16 rows / 10k chars) before
   writing the new question, and hands them to the model.

2. A full page reload (the deploy prompt's "Ladda om") closed the docked
   panel and dropped the thread from view. The panel now remembers its open
   thread per tab in sessionStorage (lib/agent-panel/session-restore) and
   the provider reopens it on mount; the sheet loads it exactly like a pick
   from "Tidigare konversationer". Close and "Ny konversation" forget it; a
   thread that no longer opens is dropped instead of retried on every reload.

3. "Can't type any more" once the update banner shows. DeployReloadPrompt's
   full-width wrapper sits at z-[60] after the panel in DOM order and
   swallowed clicks on the panel's composer; only the card takes input now.


Claude-Session: https://claude.ai/code/session_01VjoXN3xdNZrHZeYA6qMi3g

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

lib/ai/types.ts

@@ -66,11 +66,29 @@ export interface AiToolDef {
   execute: (args: Record<string, unknown>) => Promise<unknown>
 }
 
+/**
+ * One earlier turn of a conversation, text only. Sent to the model as a real
+ * message turn (not inlined into the prompt), so the answer can refer back
+ * to what was said without the caller re-describing it.
+ */
+export interface AiChatTurn {
+  role: 'user' | 'assistant'
+  text: string
+}
+
 export interface GenerateTextRequest {
   tier: AiTier
   system?: string
   prompt: string
   maxTokens: number
+  /**
+   * Earlier turns of the same conversation, oldest first, placed before
+   * `prompt` (which stays the final user message). Callers must hand over a
+   * clean alternation that starts with a user turn (see
+   * lib/agent/ask/persist.ts loadChatHistory); the services do not repair it.
+   * Absent or empty leaves the request exactly as a single-turn call.
+   */
+  history?: AiChatTurn[]
   /**
    * Read-only tools the model may call to gather data before answering. When
    * present AND the backend supports tool use (capabilities.toolUse), the