chore: add murmur-handoff skill

.claude/skills/murmur-handoff/SKILL.md

@@ -0,0 +1,54 @@
+---
+name: murmur-handoff
+description: Use when the user wants to hand off work to a fresh session — asks to "hand off", "write a handoff", "prep a prompt for another session", or types /murmur-handoff. Produces ONE self-contained prompt the user can paste into a new murmur session and run directly. With args, it captures the stated handoff requirements; with no args, it infers the next step from this session.
+---
+
+# murmur-handoff — produce a paste-ready prompt for a fresh session
+
+## What it does
+
+Emit **one fenced code block** holding a prompt the user copies into a new
+murmur session verbatim. The receiving session has none of this conversation's
+context — the prompt must stand alone. Nothing else is the deliverable; keep any
+prose around the block to a line or two.
+
+## Two modes
+
+- **With args** — the user stated what to hand off (a task, a bug, a spec step,
+  constraints). Base the prompt on that; pull in session context only to fill
+  gaps they didn't spell out.
+- **No args** — infer the handoff yourself: what was this session doing, and
+  what is the obvious next step? Read the live signals below, name that step,
+  and hand it off. State in your one line of prose what you inferred so the user
+  can correct it.
+
+## Gather before writing (cheap, do it every time)
+
+- `git status` + `git log --oneline -8` — branch, uncommitted work, recent commits.
+- `specs/STATUS.md` — the project's live current-focus.
+- Any open PR for the branch (`gh pr view` if one exists) and its CI state.
+- The thread itself — decisions made, dead ends hit, things left unfinished.
+
+## The prompt must contain (only what applies)
+
+1. **Orient** — one line: "murmur repo, branch `X`; read `CLAUDE.md` then
+   `specs/STATUS.md` first." Don't restate the routing card's content; point at it.
+2. **State** — what's already done and committed vs. still dirty/unpushed;
+   name the branch and any open PR + its CI status.
+3. **The task** — the ONE next thing, concrete and verifiable. If handing off
+   mid-build, name the spec (`spec NN`) so the receiver routes through
+   `murmur-build-spec` / `murmur-ship`.
+4. **Landmines** — decisions already settled (don't relitigate), dead ends
+   already tried, and any real-boundary caveat (unit-green ≠ delivered).
+5. **Done means** — the acceptance check that closes the task.
+
+## Rules
+
+- Self-contained: no "as we discussed", no reference to this session's messages.
+- Point to files, don't inline them — the receiver can open `CLAUDE.md`,
+  the spec, `.dev/dev.log`. Paste only facts not on disk (a decision, a failure
+  mode you hit, an in-progress diff's intent).
+- Honest state: uncommitted work, skipped steps, failing tests go in — a handoff
+  that hides them ships a landmine.
+- Lazy length: enough to act, no session-transcript dump. If it's longer than the
+  work it hands off, cut it.