Tell the M1 agent how to browse: m1-browse, not the Chrome extension

The Claude browser extension cannot work on M1 — it links to a single
persistent interactive session, and the relay runs one-shot processes. It
drives a real visible Chrome over CDP instead, so manual intervention over
screen sharing still works and logins persist.

CLAUDE.md

@@ -19,3 +19,25 @@ and do not run builds or tests here.
   rsync, never an overwrite. Then `git log` / `git status` show what changed.
 - M1 is the git remote `m1`. If something truly must be committed from here,
   push it with `git push m1 main` — but prefer telling M1 to do it.
+
+### Browsing and testing on M1
+
+M1 has **no working Claude browser extension** — that extension links to one
+persistent interactive session and cannot attach to the relay's one-shot runs.
+Use `m1-browse` instead. It drives a **real, visible Chrome** on M1 over the
+DevTools protocol, so Vincent can screen-share in and click things himself when
+something needs doing by hand; that profile keeps its own logins.
+
+```
+m1-browse open <url>          # navigate, prints title + final URL
+m1-browse text [chars]        # visible text of the current page
+m1-browse html [chars]        # page HTML
+m1-browse screenshot [path]   # PNG (default /tmp/m1-shot.png); add "full" for full page
+m1-browse click <selector>
+m1-browse type <selector> <text>
+m1-browse eval <js>           # run JS in the page, prints the result
+m1-browse tabs                # list open tabs
+```
+
+It starts Chrome itself if it is not running. To show Vincent a screenshot, take
+one and say where it is — the M5 side fetches and displays it.