docs: state plainly that ForgeFIRM is free and open source

Add a "What this costs" banner to the README and INSTALL, below the
in-development notice. It states that the firmware is free in both
senses, that nothing is paywalled or held back, that the work happens in
public, and that anyone who wants to verify it can read the licenses and
the commit log instead of taking a stranger's word for it.

The banner also warns that a build bought from a third party is that
party's build, not this project's: unreviewed code driving a laser.

Documentation only. No behavior change, so no acceptance catalog
consequence.

INSTALL.md

@@ -10,6 +10,24 @@
 > If you come across a file claiming to be a ForgeFIRM image, it did not come
 > from this project.
 
+> # What this costs
+>
+> Nothing. Not yesterday, not today, and if anyone ever charges you for
+> it, it wasn't this project. ForgeFIRM is free in both senses: free as
+> in beer, free as in speech. All of it is public, under licenses (MIT
+> and GPL) any lawyer will tell you are not a trap.
+>
+> No paid tier. No license key, no subscription, no activation, no Pro
+> edition, no product page, no waitlist, no pre-order, nothing to buy.
+> Skepticism is fair and cheap to settle: ten minutes with the licenses
+> and the commit log does it, which beats trust on both cost and
+> accuracy.
+>
+> If someone offers to sell you this firmware, the licenses allow it and
+> nobody's calling it theft. Just note that what you take home is their
+> build, not this one: a stranger's code, running a laser that has no
+> opinion about what it burns. Get it from the source.
+
 ForgeFIRM installs **alongside** the factory firmware on the stock eMMC,
 using the factory's own A/B rootfs slot scheme: the installer writes
 ForgeFIRM to the slot the factory firmware is *not* running from, and

README.md

@@ -10,6 +10,37 @@
 > If you come across a file claiming to be a ForgeFIRM image, it did not come
 > from this project.
 
+> # What this costs
+>
+> Nothing. It cost nothing yesterday, it costs nothing today, and if anyone
+> ever charges you for it, it wasn't this project.
+>
+> ForgeFIRM is free in both senses: free as in beer, free as in speech. All of
+> it is public. The image, the build layers, the kernel module, the control
+> daemon, the grblHAL driver, the cloud client, down to the brackets you print.
+> The licenses (MIT and GPL) are the standard ones, and any lawyer will tell
+> you they're not a trap. Read it, build it, change it, pass it on.
+>
+> No paid tier. No license key, no subscription, no activation, no Pro edition,
+> no feature parked behind a paywall. Nothing is held back for a rainy day,
+> mostly because there's no plan for a rainy day.
+>
+> The work happens in public, including the parts that don't work yet, which
+> are written up with more candor than flatters anyone. There's no product
+> page. No waitlist, no pre-order, no backer, no launch, nothing to buy. Anyone
+> who spends their evenings deleting sales pitches has earned the reflex to
+> suspect one more, so don't take a stranger's word for it. Ten minutes with
+> the licenses and the commit log settles it, which beats trust on both cost
+> and accuracy. Questions are welcome at
+> [the community forum](https://community.openglow.org).
+>
+> If someone offers to sell you this firmware, the licenses allow it and
+> nobody's calling it theft. Just note that you'd be paying for something
+> that's given away, and that what you take home is their build, not this one:
+> a stranger's code, running a laser that has no opinion about what it burns.
+> Get it from the source. Same price everywhere, and here you get to read what
+> you're running.
+
 Open-source firmware for Glowforge brand CNC lasers. ForgeFIRM replaces the
 cloud-dependent factory software on the **stock control board** — no hardware
 modification — and gives the machine a local controller, a local web control