htmx preset covers htmx 4; url presets become runtime predicates

[jackielii]

Closes #199.

What

htmx URL preset covers htmx 4. hx-query and hx-action join the five method attributes, and every name is sanitized in the four spellings htmx 4's attribute lookup reads: plain, :inherited, :append, :inherited:append. Verified against the htmx 4.0.0 source (#attributeValue / #determineMethodAndAction): an ancestor's hx-action:inherited wins over a child's hx-get, and hx-get:append with no inheriting ancestor is the fetch URL verbatim, so all four are sinks. hx-method names the verb and stays plain. One preset serves htmx 2 and 4; an htmx 2 page never uses the htmx 4 names. htmx's config.prefix / metaCharacter renames are not chased; the docs say to list renamed attributes under [url_attrs].

URL presets are predicates, identified by name. Expanding the preset into the user URL name list put 28 names into every spread site, allocated per render, and churned goldens on every preset edit. A preset is now a predicate compiled into internal/htmlattr (HTMXURL), applied by both static classification and the runtime spread leaf so they cannot drift. Only the name travels: as a string into the classifier fingerprint (attrclass.Rules.Presets) and as a compile-time flag into generated code (gsx.AttrSinks.Presets, gsx.PresetHTMX):

_gsxgw.Spread(ctx, "button", _gsxv0, _gsxrt.AttrSinks{Presets: _gsxrt.PresetHTMX}, []string{"class", "style"})

User [url_attrs] rules stay declarative data; there is still no user-facing predicate (4af45c4 removed one because a closure can neither reach the leaf nor hash into the cache key).

Completion data is the union of the htmx 2 and htmx 4 attribute tables: ten htmx 4 attributes added, the nine htmx 4 removed keep their entry with a "htmx 2 only" lead naming the replacement, and hx-disable documents both meanings.

Compatibility

Runtime API is additive; previously generated .x.go files with the five-name Nav list compile and render identically. Config and gen.WithURLPreset are unchanged. Generated output changes only at spread sites in projects with the preset on. The only behavioural change is the intended one: more htmx URL attributes are sanitized. Patch-level under the release policy.

Tests

• htmlattr.HTMXURL exhaustive pin (all spellings, wrong-order suffixes rejected, case folding)
• classifier: preset identity, Presets() accessor, Rules.Merge dedupe, Valid rejects unknown names, fingerprint sees presets
• runtime: AttrSinks{Presets: PresetHTMX}.sinkFor routes every spelling to the nav sink, zero value routes nothing
• codegen: every preset in attrclass.PresetNames() has a runtime flag
• corpus urlattrs/htmx_preset_v4: sanitization pinned statically and through a bag spread (the bag path can only pass via the runtime flag); bag_hx_get pins the emitted flag
• htmldata: table count, htmx 4 presence with four.htmx.org links, version notes on removed attributes

make ci exit 0 on the committed branch (the playbundle drift check diffs against HEAD, so the regenerated typebundle is in the commit).

Follow-ups (not in this PR)

• The separate URLPresets plumbing through codegen results for the LSP is now derivable from Classifier.Presets().
• Completing :inherited / :append suffix forms in the editor needs a suffix grammar in the completer, not a name list.

https://claude.ai/code/session_01Mnm5vogYqtxqUQyEvUeYbN