feat(repos): add an "Initialize mise" option to the add-repo step

Some repos an operator wants to manage don't yet define the `.mise.toml`
`[tasks.test]` task the spawn gate hard-requires — a chicken-and-egg,
since you can't run an agent to author that file without it. This adds a
one-click bootstrap.

Ticking "Initialize mise" on the add step enqueues a `mise_init` command
after the clone. The worker launches a dedicated agent that detects the
repo's stack, writes a `.mise.toml` with a canonical `[tasks.test]` task,
and commits + pushes it. That agent runs with the test-task gate off
(creating the task is the point) and a `HANDLER_MISE_INIT` marker on, so
its hooks enforce a bootstrap contract instead of the normal test gate:

- Stop hook blocks the turn until `.mise.toml` defines `[tasks.test]` and
  the change is committed (clean tree) and pushed (no commits ahead of an
  upstream) — so claude cannot end before the work has actually landed.
- git-push hook lets the bootstrap push through, skipping the test/build
  gate (there may be no working suite yet) so the file reaches the remote.

Backend: `mise_init` command type (+ migration 0006), a shared
`control.mise` helper for the test-task check, `spawn(require_tests=,
mise_init=)`, gitops `is_clean`/`ahead_count`, and `init_mise` on the
project-create API (only acts when a git remote exists to push to).
Frontend: the checkbox, plumbed through the store, following the launch.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BxKY28XKCM6o4ag3nmaVsZ

frontend/components/sections/RepositoriesSection.tsx

@@ -22,6 +22,7 @@ const empty: NewProjectBody = {
   root_dir: "",
   git_remote: "",
   credential_ref: "",
+  init_mise: false,
 };
 
 export function RepositoriesSection() {
@@ -163,6 +164,28 @@ export function RepositoriesSection() {
             </>
           )}
 
+          {!editing && (
+            <label className="hstack" style={{ gap: 8, cursor: "pointer", marginTop: 14 }}>
+              <input
+                type="checkbox"
+                checked={form.init_mise}
+                onChange={(e) => setForm({ ...form, init_mise: e.target.checked })}
+              />
+              <span style={{ fontSize: "var(--text-sm)" }}>
+                Initialize mise — after the clone, run an agent that writes a{" "}
+                <span className="mono">.mise.toml</span> with a{" "}
+                <span className="mono">[tasks.test]</span> task for this repo&rsquo;s stack, then
+                commits and pushes it. Needed for repos that don&rsquo;t define one yet.
+              </span>
+            </label>
+          )}
+          {!editing && form.init_mise && form.mode === "manual" && !form.git_remote.trim() && (
+            <p className="faint" style={{ fontSize: "var(--text-xs)", margin: "6px 0 0" }}>
+              A git remote is required to push the new <span className="mono">.mise.toml</span> —
+              add one above, or mise won&rsquo;t be initialized.
+            </p>
+          )}
+
           <div className="hstack mt14">
             <Button variant="primary" disabled={s.cmd.busy || !canSave} onClick={save}>
               {editing ? "Save changes" : form.mode === "server" ? "Add & pull" : "Register"}