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/components/InputBar.svelte

@@ -248,7 +248,7 @@
     const hasAttachments = attachments.length > 0;
 
     // Need either a message or attachments to submit
-    if ((!message && !hasAttachments) || isSubmitting) return;
+    if ((!message && !hasAttachments) || isSubmitting || isProcessing) return;
 
     // Check for slash commands first (these work even when disconnected)
     if (message && isSlashCommand(message)) {
@@ -339,6 +339,7 @@ User: ${formattedMessage}`;
         conversationId,
         message: messageToSend,
       });
+      claudeStore.setProcessing(true);
     } catch (error) {
       console.error("Failed to send prompt:", error);
       claudeStore.addLine("error", `Failed to send: ${error}`);
@@ -768,7 +769,7 @@ User: ${formattedMessage}`;
 
   async function handleQuickAction(prompt: string): Promise<void> {
     // Quick actions send the prompt directly
-    if (!isConnected || isSubmitting) return;
+    if (!isConnected || isSubmitting || isProcessing) return;
 
     // Add to history
     addToHistory(prompt);
@@ -793,6 +794,7 @@ User: ${formattedMessage}`;
         conversationId,
         message: prompt,
       });
+      claudeStore.setProcessing(true);
     } catch (error) {
       console.error("Failed to send quick action:", error);
       claudeStore.addLine("error", `Failed to send: ${error}`);
@@ -1018,7 +1020,7 @@ User: ${formattedMessage}`;
         placeholder={isConnected
           ? "Ask Hikari anything... (type / for commands)"
           : "Connect to Claude first..."}
-        disabled={isSubmitting}
+        disabled={isSubmitting || isProcessing}
         rows={1}
         style="height: {textareaHeight}px; font-size: var(--terminal-font-size, 14px); font-family: var(--terminal-font-family, monospace);"
         class="w-full px-4 py-3 bg-[var(--bg-secondary)] border border-[var(--border-color)]