feat: agent concurrency, conversation summaries, AI tools config, UI polish

- Agent slot limiter for concurrent tool execution
- Conversation summarization with soft-delete (MarkSummarized)
- ANSI stripping in terminal tool output
- Configurable crush-run timeout (default 600s, max 900s)
- Starship theme refactor, AI tools config grid, system update UI
- Streaming segments refactor, summarized messages block in feed
- CSS: headings, scrollbars, tool cards, summary block styles
- i18n additions (en+fr) for tools, updates, config

💘 Generated with Crush

Assisted-by: GLM-5.1 via Crush <crush@charm.land>

web/src/i18n/en.js

@@ -211,8 +211,27 @@ const en = {
     resetConfirm: 'Are you sure? All preferences will be erased.',
     resetDone: 'Settings reset.',
     applyStarship: 'Apply starship',
+    apply: 'Apply',
+    remove: 'Remove',
     starshipApplied: 'Starship theme applied! Restart your shell to see the result.',
     starshipError: 'Failed to apply starship theme.',
+    systemConfig: 'System Configuration',
+    aiToolsConfig: 'Tools & Environments',
+    configureViaAI: 'Configure',
+    toolCrushDesc: 'Autonomous AI agent for code writing and refactoring.',
+    toolClaudeDesc: 'AI coding assistant by Anthropic.',
+    toolGhDesc: 'Command-line interface for GitHub.',
+    toolDockerDesc: 'Application containerization platform.',
+    toolGoDesc: 'Programming language and runtime environment.',
+    toolNodeDesc: 'JavaScript runtime and package manager.',
+    toolPythonDesc: 'Programming language, pip and uv manager.',
+    toolStarshipDesc: 'Modern and customizable shell prompt.',
+    systemUpdate: 'System Update',
+    systemUpdateDescSudo: 'Updates the system and all tools (sshpass, crush, claude, gh, etc.).',
+    systemUpdateDescNoSudo: 'Shows update commands to run manually.',
+    updateBtn: 'Update',
+    notInstalled: 'Not installed',
+    install: 'Install',
   },
 }