Pricing updates.

Take the prices off the Plans page and point at the storefront (#118)

* docs(plans): take the prices off the page and point at the storefront

Closes #105.

The page carried live commercial terms in a repository that accepts outside
pull requests: per-node prices, node minimums, a volume-discount table with
thresholds and savings percentages, a worked forty-node calculation, and the
annual prepayment discount. A docs PR should not be able to change what the
product costs.

It also duplicated a surface the repo already treats as canonical. Four retired
pages -- Toolkit, the ROI calculator, Offers and Discounts -- already redirect to
immersivefusion.com/pricing. Plans was simply never swept with them, and a
second copy of a price list is a copy that drifts.

Removed with them, per Friday on bus #2337: the Uptime SLA row and the matching
per-plan bullets. The figures did match the finance model, unlike the retired
SLA page's, but an uptime commitment on a public page is a contractual
instrument and nothing establishes it has been approved for publication. Same
reasoning that retired Resources/Legal/sla.md in #104.

Also from #2337: "Enterprise SLA, 50+ nodes" in the plan-choosing table became
"Largest deployments, 50+ nodes". Enterprise is not one of our tiers, and this
is the adjectival use that most likely manufactured the Starter/Professional/
Enterprise set in the first place.

What stays is what a docs page should answer: what each plan does. Throughput,
retention, AI budget, support channels, infrastructure, and which capabilities
each tier includes. Retitled from "Plans & Pricing" to "Plans", since it no
longer carries pricing, and the inbound link from the OpenTelemetry page is
updated to match.

Not verified, and left as found rather than re-asserted: the throughput,
retention and AI query figures. They come from the same finance model as the
uptime numbers and I have no confirmation they are approved for publication.
Flagged rather than silently blessed by touching the page around them.

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

* docs(plans): put the uptime figures back

I removed them against an explicit instruction. Friday's ruling on bus #2337
says, in the WHAT TO DO block:

  "Plans page: rename Free to Start (free). Uptime figures already match
   canon; leave them."

The same reply also said "I would not publish the canon numbers either", and
marked that sentence, in capitals, A FLAG NOT A RULING. It was written about the
legal SLA page in the context of PR #104 retiring it, not about this table.

I promoted the advisory aside over the instruction and removed rows Friday had
told me to keep. The figures match docs/finance/pricing.md line 48 and belong on
a plan comparison: uptime by tier is one of the first things a buyer compares,
and Fuse at 99.99% is a selling point rather than a liability.

Restored: the Uptime SLA row and the three per-plan bullets. The pricing
removals in this PR stand, since those rest on their own reasoning -- commercial
terms in a repository that accepts outside pull requests, duplicating a
storefront the repo already treats as canonical.

Friday's flag is still worth answering, and is worth answering properly rather
than by my unilateral deletion: whether an uptime commitment sourced from a
finance model has been approved for publication is a legal question. Raising it
separately.

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

* docs(plans): say that changing tiers costs money

The Changing Plans section walked a user through four steps to switch tiers and
never mentioned a fee. The storefront states a one-time charge for a tier change,
with same-tier node adjustments free. Someone following this page would follow
the steps and be charged without warning.

Found while checking whether dropping the volume-discount tables from this PR
was safe. It was: the storefront carries the per-node prices, the discount above
minimum, the node minimums and the annual prepayment discount, and carries them
more completely than this page did -- it also has Tessa seat pricing and this
fee, neither of which was ever here. The docs copy was a stale subset, which is
the argument for pointing at one surface rather than maintaining two.

The amount is deliberately not repeated here. Naming a figure recreates exactly
the drift this PR removes; saying a fee exists and linking to where it is stated
does not.

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

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Co-authored-by: Claude Opus 5 <noreply@anthropic.com>