feat(project-coordinator): offer to keep a history of a project

A project folder accumulates work with no way to see what changed or undo a
wrong turn. The coordinator now offers to keep one, once, in plain words, and
initializes it only after an explicit yes — the mechanism is git in the sandbox
but the jargon stays out of the conversation, since the person being offered
this is not necessarily someone who knows what a commit is. That first yes is
standing consent to snapshot at later milestones, so the agent does not re-ask
each time.

Recorded in the project's SKALD.md so a future session knows the history exists
rather than proposing it again, and documented in docs/projects.md, which is
what the assistant reads to explain the feature to a user.

agents/project-coordinator/AGENT.md

@@ -90,6 +90,16 @@ Then add a clear `## TASK` section describing exactly what you want done. You ca
 
 ---
 
+## Suggest keeping a project history
+
+Any project can grow worth keeping a **history** of — seeing what changed, or undoing a wrong turn. Offer this early on, in **plain, non-technical words** adapted to the project's nature ("I can keep a history of this project, so we can always look back at what changed or return to an earlier version — want me to?"). Propose it once; if the user declines, don't push.
+
+The mechanism is **git** (available in the sandbox), but keep the jargon out of the conversation. Initialize only after an **explicit yes**: run `git init` in the project folder via `execute_cmd` and make a first commit (set a repo-local identity if asked, e.g. `git config user.name "Skald"`). Then note it in `SKALD.md` ("Versioned with git since … — commit at meaningful milestones") so future sessions know.
+
+From then on, **commit at meaningful milestones** — a draft finished, a plan agreed, a feature done — with a short message, and mention it casually ("I've saved a snapshot of this stage"). The initial yes is your standing consent; don't re-ask each time.
+
+---
+
 ## Keep `SKALD.md` up to date
 
 `SKALD.md` (project root) is this project's living diary — the equivalent of personal memory, but scoped to this project. Keep it current so a future conversation resumes with full context. Record there: the goal and scope, key decisions made, current status, useful references (paths to research reports, drafts, specs), and the next steps. Update it with `write_file` / `edit_file` whenever something durable changes — don't let it go stale. If it doesn't exist yet, create it the first time the project has state worth remembering.

docs/projects.md

@@ -73,3 +73,4 @@ Access changes apply immediately — no need for the other person to log out.
 - A private project is simply a project with one member (you). Share it later whenever you want.
 - Renaming a project does not move its folder, so links and the assistant's context keep working.
 - Deleting a project removes its folder for everyone — there is no undo.
+- The assistant may offer to **keep a history** of the project: a trail of snapshots you can look back on, or return to if something goes wrong. If you accept, it notes that in the project's `SKALD.md` and saves a new snapshot whenever the project reaches a meaningful milestone. The history lives inside the project folder on the server (it is powered by git, but you never need to touch it).