refactor(vscode-ide-companion): migrate session save to CLI /chat save command

- Replace manual checkpoint file writing with CLI's native /chat save command
- Add saveCheckpointViaCommand method to use CLI's built-in save functionality
- Deprecate saveSessionViaAcp as CLI doesn't support session/save ACP method
- Update saveCheckpoint to delegate to CLI command for complete context preservation
- Enhanced error logging in acpSessionManager session load
- Mark saveSessionViaAcp as deprecated with fallback to command-based save
- Fix ESLint errors: remove unused imports and catch variables, wrap case block declarations

This ensures checkpoints are saved with complete session context including tool calls,
leveraging CLI's native save functionality instead of manual file operations.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

packages/vscode-ide-companion/src/webview/ClaudeCodeStyles.css

@@ -282,84 +282,6 @@
   --app-warning-foreground: var(--vscode-editorWarning-foreground, #ffcc00);
 }
 
-/* ===========================
-   Tool Call Card (from Claude Code .Ne)
-   =========================== */
-.tool-call-card {
-  border: 0.5px solid var(--app-input-border);
-  border-radius: 5px;
-  background: var(--app-tool-background);
-  margin: 8px 0;
-  max-width: 100%;
-  font-size: 1em;
-  align-items: start;
-}
-
-/* Tool Call Grid Layout (from Claude Code .Ke) */
-.tool-call-grid {
-  display: grid;
-  grid-template-columns: max-content 1fr;
-}
-
-/* Tool Call Row (from Claude Code .no) */
-.tool-call-row {
-  grid-column: 1 / -1;
-  display: grid;
-  grid-template-columns: subgrid;
-  border-top: 0.5px solid var(--app-input-border);
-  padding: 4px;
-}
-
-.tool-call-row:first-child {
-  border-top: none;
-}
-
-/* Tool Call Label (from Claude Code .Je) */
-.tool-call-label {
-  grid-column: 1;
-  color: var(--app-secondary-foreground);
-  text-align: left;
-  opacity: 0.5;
-  padding: 4px 8px 4px 4px;
-  font-family: var(--app-monospace-font-family);
-  font-size: 0.85em;
-}
-
-/* Tool Call Value (from Claude Code .m) */
-.tool-call-value {
-  grid-column: 2;
-  white-space: pre-wrap;
-  word-break: break-word;
-  margin: 0;
-  padding: 4px;
-}
-
-.tool-call-value:not(.expanded) {
-  max-height: 60px;
-  mask-image: linear-gradient(to bottom, var(--app-primary-background) 40px, transparent 60px);
-  overflow: hidden;
-}
-
-.tool-call-value pre {
-  margin-block: 0;
-  overflow: hidden;
-  font-family: var(--app-monospace-font-family);
-  font-size: 0.85em;
-}
-
-.tool-call-value code {
-  margin: 0;
-  padding: 0;
-  font-family: var(--app-monospace-font-family);
-  font-size: 0.85em;
-}
-
-/* Tool Call Icon (from Claude Code .to) */
-.tool-call-icon {
-  margin: 8px;
-  opacity: 0.5;
-}
-
 /* Code Block (from Claude Code ._e) */
 .code-block {
   background-color: var(--app-code-background);
@@ -432,37 +354,3 @@
   color: var(--app-secondary-foreground);
   font-size: 0.85em;
 }
-
-/* Status indicators for tool calls */
-.tool-call-status-indicator {
-  display: inline-flex;
-  align-items: center;
-  gap: 4px;
-}
-
-.tool-call-status-indicator::before {
-  content: "●";
-  font-size: 10px;
-}
-
-.tool-call-status-indicator.pending::before {
-  color: var(--app-secondary-foreground);
-}
-
-.tool-call-status-indicator.in-progress::before {
-  color: #e1c08d;
-  animation: blink 1s linear infinite;
-}
-
-.tool-call-status-indicator.completed::before {
-  color: #74c991;
-}
-
-.tool-call-status-indicator.failed::before {
-  color: #c74e39;
-}
-
-@keyframes blink {
-  0%, 100% { opacity: 1; }
-  50% { opacity: 0; }
-}