Add Claude Code settings infrastructure, TUI mode, session naming, and global defaults

Adds first-class support for Claude Code CLI features (2.1.71-2.1.110):

- New ClaudeCodeSettings struct with per-project and global defaults for
  TUI mode, effort level, focus mode, thinking summaries, session recap,
  auto-scroll, env scrub, and 1-hour prompt caching
- Settings injected as env vars (CLAUDE_CODE_NO_FLICKER, etc.) and
  ~/.claude/settings.json entries via entrypoint.sh merge block
- New ClaudeCodeSettingsModal component for configuring settings
- Session naming support (-n flag passed to claude CLI, shown in tabs)
- Relaxed reserved prefix filter: CLAUDE_CODE_* env vars now allowed in
  custom env vars UI for power users
- Global SSH key path, git name, and git email now used as fallbacks
  when per-project values are not set, with UI in SettingsPanel
- Fingerprint-based change detection triggers container recreation when
  Claude Code settings change
- Updated README, HOW-TO-USE, and CLAUDE.md documentation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/src/components/terminal/TerminalTabs.tsx

@@ -23,8 +23,8 @@ export default function TerminalTabs() {
               : "text-[var(--text-secondary)] hover:text-[var(--text-primary)]"
           }`}
         >
-          <span className="truncate max-w-[120px]">
-            {session.projectName}{session.sessionType === "bash" ? " (bash)" : ""}
+          <span className="truncate max-w-[140px]">
+            {session.sessionName ?? session.projectName}{session.sessionType === "bash" ? " (bash)" : ""}
           </span>
           <button
             onClick={(e) => {