fix: correct tool call card rendering on session load after context compaction (#408)

* fix: correct tool call card rendering on session load

Two bugs caused duplicate/incorrect tool call cards when loading
sessions (especially after context compaction):

1. loadSession() sanitized messages (B9 filter) but did NOT update
   the session-level tool_calls array's assistant_msg_idx references.
   Since compact() returns only sanitized messages and recomputes
   tool_calls with indices into the compacted array, the original
   assistant_msg_idx values became stale/misaligned.

2. loadSession() then assigned the broken session-level tool_calls
   directly to S.toolCalls. This prevented renderMessages()'s fallback
   path (which derives tool_calls from per-message tool_calls using
   correct sanitized-array indices) from ever running.

Fix:
- Keep full sanitization loop with index remapping for session-level
  tool_calls (in case they're needed by other code paths).
- Instead of assigning broken session-level tool_calls to S.toolCalls,
  set S.toolCalls=[] so renderMessages() uses the fallback derivation
  from per-message tool_calls, which already have correct indices.

* test: add 8 regression tests for issue #401 tool call index remapping

* docs: v0.50.29 release — version badge and CHANGELOG

---------

Co-authored-by: Frank Song <franksong2702@gmail.com>
Co-authored-by: Nathan Esquenazi <nesquena@gmail.com>

static/index.html

@@ -535,7 +535,7 @@
                 <div class="settings-section-title">System</div>
                 <div class="settings-section-meta">Instance version and access controls.</div>
               </div>
-              <span class="settings-version-badge">v0.50.28</span>
+              <span class="settings-version-badge">v0.50.29</span>
             </div>
             <div class="settings-field" style="border-top:1px solid var(--border);padding-top:12px;margin-top:8px">
               <label for="settingsPassword" data-i18n="settings_label_password">Access Password</label>