Let the master dashboard drive this instance; drop the AutoBuyer switch

Three changes that ride together because they touch the same surface.

A control link to the master. lib/master-link.ts dials out to
<master>/ws/instance and holds it open, so the dashboard can trigger a trade or
queue an AutoBuyer run here. Commands call the same functions the local pages
call — runTrade, startScheduler, queueRun — so nothing reaches the broker by a
path the UI does not also use. Reports prefer the socket and fall back to the
existing POST, which keeps older masters working unchanged.

startMasterLink is idempotent, and that matters more than it looks: getClients()
is lazy and starts the link, so the first command re-enters it from inside a
command the live socket is waiting to ack. Tearing the socket down there loses
the ack and reports a trade that actually executed as a failure — which invites
pressing the button twice.

queueRun is lifted out of the automations route so the socket and HTTP share one
copy of the input clamping that decides how many times a purchase fires.

Page capture loses its switch and gains a scope. It now runs every tick, but
only against the active tab of the last-focused window that matches
host_permissions — so it follows the page in front of you and stops when you
switch away, where before it would fall back to any firm tab left open in the
background.

autobuyer_enabled is gone entirely. The AutoBuyer is ready whenever the runner
is; a run happens because someone asked for one. That does mean a queued run
executes as soon as clicker/runner.py claims it, with no second gate — stopping
the runner is now the way to make a machine idle.

Extension to 0.10.0; it needs a manual reload at chrome://extensions.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -79,6 +79,38 @@ Open the app in your browser and add your firms through the UI:
 
 ---
 
+## The master dashboard
+
+Set **Instance Name** and **Dashboard URL** on the Settings page and this
+instance does two things with them: it reports its firm and account counts every
+30 seconds, and it holds a WebSocket open to `<url>/ws/instance` so the master
+can drive it.
+
+What the master can trigger here:
+
+| | |
+|---|---|
+| Trade | Buy / Sell / Auto on a symbol, with the same "stop after all" option as the button on this dashboard |
+| Stop | Halts the auto-trade scheduler |
+| Run an automation | Queues a run for `clicker/runner.py`, exactly as the AutoBuyer page does |
+
+Commands land in [`lib/master-link.ts`](lib/master-link.ts), which calls the same
+functions the pages call — `runTrade`, `startScheduler`, `queueRun`. Nothing
+reaches the broker by a path the local UI does not also use, and every command
+is acked with its result or its error so the master shows what actually happened
+rather than assuming.
+
+The link is entirely optional. With no Dashboard URL configured it never starts,
+and if the master is unreachable the instance keeps trading on its own and falls
+back to the plain HTTP report until the socket comes back (retrying with backoff,
+capped at a minute).
+
+**Nothing authenticates this link in either direction.** Whatever answers at the
+Dashboard URL can place orders on every account this instance holds, so point it
+only at a master you control, and prefer `https` so the address cannot be
+redirected in transit. If the socket will not stay up, the `connected` light on
+the master is the only symptom — check this instance's logs for `[master-link]`.
+
 ## AutoBuyer (browser automation)
 
 The AutoBuyer page drives a real browser to buy and reset prop-firm accounts. It
@@ -136,8 +168,17 @@ dashboard warns when its version is behind.
 
 ### Running it
 
-Turn **Page capture** on from the AutoBuyer page, then press an automation's
-button. Progress appears per step, and **Stop** halts a run between steps.
+Press an automation's button. Progress appears per step, and **Stop** halts a run
+between steps.
+
+There is no switch to throw first. Page capture follows whichever firm tab you
+are looking at and stops when you switch away, and a run starts because someone
+asked for one — from this page or from the master dashboard. The only thing that
+gates a run is whether `clicker/runner.py` is up to claim it, which the page
+shows as **Autoclicker daemon**.
+
+That does mean a queued run executes as soon as the runner sees it, with no
+second confirmation. Stop the runner if you want the machine idle.
 
 The browser must be visible and frontmost while a run is in flight — the clicks
 are real OS-level input, so the machine cannot be used for anything else, and a