fix: resolve message submission and stuck processing bugs (#199)

## Summary

- **Fix `isProcessing` tracking**: The `isProcessing` store field was initialised as `false` and never set to `true` in production, making all submission guards no-ops. Now `setProcessing(true)` is called after `send_prompt` succeeds in both `handleSubmit` and `handleQuickAction`, and `setProcessingForConversation(id, false)` is called when the backend emits an idle/success/error state.
- **Fix auto-granted tools dropped on permission reconnect** (closes #198): `PermissionModal.svelte` was passing only session-granted tools when reconnecting after a permission approval, silently dropping `config.auto_granted_tools`. Fixed to merge both sets, matching the behaviour of every other `start_claude` call site.
- **Add mid-session watchdog**: A watchdog thread now kills the Claude Code process if a user message is sent but no `Result` arrives within 5 minutes. This triggers the existing disconnect/error flow so the user is notified and can reconnect. A generation counter ensures watchdogs from previous sessions exit cleanly when a new session starts.

## Test plan

- [ ] Send a message and verify the textarea is disabled and the stop button is visible while Claude is processing
- [ ] Verify the textarea re-enables after Claude finishes responding
- [ ] Enable a tool in default permissions (e.g. Read), start a session, trigger a permission approval for another tool, approve it — verify the previously auto-granted tool is no longer re-prompted
- [ ] Verify all existing tests pass (`./check-all.sh`)

✨ This PR was created with help from Hikari~ 🌸

Reviewed-on: #199
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

src/lib/tauri.ts

@@ -236,9 +236,10 @@ export async function initializeTauriListeners() {
         );
       }
 
-      // Update character state for this conversation
+      // Update character state and processing state for this conversation
       if (targetConversationId) {
         claudeStore.setCharacterStateForConversation(targetConversationId, "idle");
+        claudeStore.setProcessingForConversation(targetConversationId, false);
       }
     } else if (status === "error") {
       const targetConversationId = conversation_id || get(claudeStore.activeConversationId);
@@ -333,13 +334,21 @@ export async function initializeTauriListeners() {
     }
 
     // Always update the conversation's state
+    const isTerminalState =
+      mappedState === "idle" || mappedState === "success" || mappedState === "error";
     if (conversation_id) {
       claudeStore.setCharacterStateForConversation(conversation_id, mappedState);
+      if (isTerminalState) {
+        claudeStore.setProcessingForConversation(conversation_id, false);
+      }
     } else {
       // Fallback to active conversation if no conversation_id
       const activeConversationId = get(claudeStore.activeConversationId);
       if (activeConversationId) {
         claudeStore.setCharacterStateForConversation(activeConversationId, mappedState);
+        if (isTerminalState) {
+          claudeStore.setProcessingForConversation(activeConversationId, false);
+        }
       }
     }