fix(omp): resume by mode, not silently as claude, and support --continue

resumeHistorySession() never sent mode when recreating a session from a
history/session-manager row, so the server default silently opened a
plain Claude session for every non-claude row -- reproduced live: OMP
rows spawned Claude sessions on click. Thread the row's mode through
every call site (welcome list, session manager, mobile overview) and
only send the Claude-specific resumeSessionId for claude rows.

Codeman has no live PTY-reattach outside server boot, and it's moot for
OMP anyway (exiting it kills the pane's only process), so route the
non-claude relaunch through each CLI's own continue-most-recent flag
instead of a context-free fresh start. OMP never got one: buildOmpCommand
only implemented --model/--resume despite omp --help documenting
-c/--continue. Added continueSession to OmpConfig end-to-end (type,
schema, builder) mirroring the existing opencode/pi/grok/deepseek
fields, and wired resumeHistorySession to use it.

Verified live: told a real omp session a secret, exited it, closed the
tab without killing tmux, relaunched with --continue in the same
directory, and had it recall the secret.

src/web/public/mobile-overview.js

@@ -389,7 +389,7 @@ Object.assign(CodemanApp.prototype, {
   async resumeMobileOverviewSession(sessionId) {
     const row = (this._mobileOverviewPastRows || []).find((r) => r.id === sessionId);
     if (!row || !row.workingDir) return;
-    await this.resumeHistorySession(row.claudeSessionId || row.id, row.workingDir, row.name || undefined);
+    await this.resumeHistorySession(row.claudeSessionId || row.id, row.workingDir, row.name || undefined, row.mode);
   },
 
   // ═══════════════════════════════════════════════════════════════