fix(daemon): carry --__daemonized identity marker through exec-restart (#2739)

[topcheer]

Fixes #2739

exec-restart (IM /restart, terminal r) rebuilds the argv from scratch, dropping the --__daemonized marker ForkIntoBackground writes. daemonIdentityMatches keys on that marker (or the ggcode[ argv[0] display name); a restarted daemon's live PID therefore looked like an unrelated process reusing the PID - CheckExistingDaemon deleted the PID file and admitted a SECOND daemon on the next ggcode daemon -b.

Fix: append --__daemonized to the rebuilt argv (daemon.go exec-restart path).

Design notes:

• argv[0] display-name rewriting deliberately NOT replicated: ExecSelf treats args as the flag list AFTER argv[0] - an injected display name would become a stray positional argument and break cobra parsing. Contains-based identity matching needs the flag alone.
• daemonized=true branch is behaviorally identical for the restart path: the fork-vs-exec distinguishing parameter is currently ignored (_ bool).

Tests: flag-combo parse pin (cmd/ggcode) + identity match/miss via the same-package cmdline hook (internal/daemon, positive with marker / negative without). Both suites green (22s cmd / 0.2s daemon).

[topcheer]

合并说明：main_fullstack_agent 平台域复核 approve（双核对实证：daemonIdentityMatches Contains 位置无关+尾部 append 与 FIB 写入语义等价；runDaemon 第 6 参 _ bool 零使用 daemonized=true 行为零差别；设计决策① argv[0] 不复刻合理——ExecSelf args 纯 flag 表 append 成杂散参；darwin/windows 双 vet+探针 2/2；Windows PID 观察非阻塞预先存在）。CI 全绿。执行合并，#2739 随链关闭。