mksh: backslash-escape commands in history hook to bypass module aliases (wc=tokei, tr=transmission-remote, cat=bat)

mksh: reliable history hook via HISTFILE growth + binary record parse

PS1 command substitution runs in a subshell so hook state must be
persisted to disk (per-PID file); fc there is lagged one command and
drops each session's last command. Detect new commands by HISTFILE
growth and parse the last record from mksh's on-disk format.

mksh: skip stale history log on first prompt render

mksh: port bashisms to mksh-safe (process subs, DEBUG-trap history hook, direnv, cd- alias)

wip: emergency backup (power outage risk)

sync: lock down plan9 theme, wallpapers, nvim configs

- setbg: add -w (wallpaper-only), -d (default plan9 theme), terminal color reset
- wallpapers: plan9.png, plan9theme.png, plan9-grey.png, d1e2f1-horizontal
- nvim: add code/ and write/ NVIM_APPNAME configs (vacme + writing themes)
- bin: add write, code scripts (replace shell functions)
- xprofile: caps:none, dpms off, setfan, gnome-keyring, wireplumber, conky, protonmail
- wal: add colors-dwm-xresources template, remove stale btop.theme
- conky: add clock.conf, clock.lua, local.conf

shell migration: fish -> mksh, reorganize bin/, wallpaper cleanup

- replace fish config with .profile (POSIX login) and .mkshrc (interactive)
- organize .local/bin into subdirs: academic, cron, dev, dmenu, history,
  media, misc, monitoring, nnn, security, statusbar, system
- all subdirs added to PATH, scripts callable by name from anywhere
- remove fish config, .config/shell/aliasrc, .config/shell/profile
- consolidate sb-* scripts into statusbar/ (updated stale copies)
- convert wallpapers to webp, slug-WxH naming scheme
- regenerate plan9 solid fills at proper monitor dimensions
- fix larbs -> lazykris path refs across scripts
- remove remapd from both xprofile files
- fix bashism shebangs (11 scripts: #!/bin/sh -> #!/bin/bash)
- update bm-dirs/bm-files for current home layout
- update emoji set to Unicode 15.0 (3655 entries)
- merge push + push-smart into single script with --smart flag
- delete one-off scripts, convert trivial wrappers to aliases