feat(lint): add the stx conformance checks to buddy lint

[glennmichael123]

Redo of the closed #2206, in the shape you asked for:

./buddy lint:stx i dont think should be command either / buddy lint is fine / buddy lint --stx reads better, because there will be more options then just stx

./buddy lint --stx

What #2206 got wrong

then	now
.stx-gate.json dotfile in the repo root	config/lint.ts, typed LintConfig, alongside the other 45 configs
a stx-gate-types.ts nothing imported	types declared where they are used
--update rewrote the baseline file	the linter never writes to source; a stale baseline prints the counts ready to paste
its own top-level command	a flag on the existing one

The dotfile was the worst of it — config/ui.ts documents the convention in its own comment ("Stacks keeps every runtime-owned directory under storage/ rather than a .stx in the project root") and I put a JSON dotfile in the root anyway.

What it checks

Chapter 12 of the stx standards, plus three that read the build output. Those three exist because a real bug shipped past every source-level check: a mis-resolved component put an error string where the sidebar should have been on every built page, so the app shipped with no navigation and the developer's home directory in the HTML — and the build still exited 0.

A ratchet, not a cliff

Counts are compared against config/lint.ts baselines, and the check fails both above a baseline and below one. Clearing a violation has to be recorded rather than quietly banked. A check with no entry is held at zero, so one added by a framework upgrade starts strict rather than inheriting whatever the project happens to have.

Stacks' own baselines

Shipped with it, each non-zero entry naming what clears it:

check	count	clears when
stx-config-keys	3	config/ui.ts sets strict/root/pagesDir
doctype-no-nolayout	5	stacksjs/stx#1798 lands generateDocumentShell htmlAttrs
style-block	2	the two remaining <style> blocks move to crosswind preflights
dom-guard	3	coming-soon.stx / index.stx move to signals
inline-style-attr	49	desktop demo components + pre-hydration display:none
plain-internal-anchor	1	index.stx's brand link becomes StxLink

stx-config-keys is recorded as debt rather than fixed in passing: pinning root+pagesDir changes how stx resolves topology and wants its own dev+build pass, which is not a change a linter should make on a project's behalf.

Not wired into CI. The framework does not pass its own checks yet, and turning a red gate on is a separate decision from making the tool exist.

Verification

Ratchet exercised both directions (regression → exit 1, stale baseline → exit 1 with the paste block), plain buddy lint unaffected, 241 buddy tests pass, pickier clean, framework + app typechecks clean, command reference regenerated and passing.

Once this lands, postline's scripts/stx-gate.ts gets deleted rather than annotated — my note-adding commit there was the wrong call.

🤖 Generated with Claude Code