feat(notify-me): add skill

Notify at the end of any turn long enough that the operator has
probably looked away, asked or not. opencode-web notifies on every
reply, which is too much; silence let a long turn sit unseen. -t 0
keeps a notice up through a walk (tested on MATE: the default notice
expired; the -t 0 one stayed until closed).

An experiment in form: the body is a Portland Pattern Repository
pattern (context, problem, forces, therefore, resulting context),
after Alexander, rather than the usual rules-and-recipe skill.

The tension: forces give an agent reasons to handle cases the rules
don't anticipate, and make the trade-offs visible to whoever edits
the skill next; but the form runs longer, and every word is paid on
each load, with the actionable part buried under the preamble.

The resolution: an example notify-send right under the h1, the
forces cut to one line each, and the description left in matcher
form. The result is shorter than the rules-style draft (459 words vs.
562). Resulting context: if it reads well in practice, judgment-call
skills may adopt the form; recipe skills (retcon, yarn.lock) likely
gain little from it.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

README.md

@@ -53,6 +53,8 @@ Code](https://code.claude.com/docs/en/skills) and
   a throwaway systemd user unit that can't see `~/.ssh` and friends.
 - [what-was-i-doing](what-was-i-doing/SKILL.md) — where did this file
   come from? Correlate mtimes with git history across every repo.
+- [notify-me](notify-me/SKILL.md) — desktop notification at the end
+  of a long turn, sticky if I'm stepping away; not every reply.
 
 ## adding one