…urate tag cloud

Five recently-added Grails 8 guides (multi-module, rest-library, github-actions-cicd)
plus three older entries (grails-as-docker-container, grails-mock-basics v4,
creating-your-first-grails-app v6) were silently absent from
https://grails.apache.org/guides/ even though their per-guide HTML was
built and uploaded correctly. Three independent bugs combined to make
this happen, and the bottom-of-page category grid was simultaneously
overweight on dead/legacy stacks while missing the modern Web Layer
section that every flagship Grails 8 guide lives in.

== conf/guides.yml: 5 sampleRef.repo collisions ==

The fetcher used to group guide-versions by sampleRef.repo, so any two
YAML entries that happened to point at the same external repo merged
into a single rendered guide and clobbered each other. Five YAML entries
were pointing at the wrong repo (the new Grails 8 sample repo instead of
their own legacy repo):

  - grails-as-docker-container v3, v4 -> grails-as-docker-container
    (was grails-docker-bootbuildimage; collided with grails-docker-bootbuildimage v8)
  - grails-multi-project-build v4 -> grails-multi-project-build
    (was grails-multi-module; collided with grails-multi-module v8)
  - rest-hibernate v3, v4 -> rest-hibernate
    (was grails-rest-library; collided with grails-rest-library v8)
  - grails-on-github-actions v4 -> grails-on-github-actions
    (was grails-github-actions-cicd; collided with grails-github-actions-cicd v8)

These look like the residue of repo renames that were applied in the
sample registry but never propagated to the new entries that needed
distinct slugs.

== GuidesFetcher: identify guides by YAML name, not sampleRef.repo ==

Even with the YAML cleaned up, the fetcher was structurally fragile.
It also had two latent bugs:

1. BRANCH_TO_MAJOR map hardcoded master->4 and was missing grails7,
   grails8. creating-your-first-grails-app/v6 (whose sampleRef.branch
   is master) was silently mapped to major version 4, overwriting the
   real v4 entry in grailsMayorVersionTags. The v6 build was reachable
   only via direct URL.
2. grails-mock-basics had v3 and v4 both with branch=master under one
   guide. The slug+branch grouping reduced to {master}, so size==1
   triggered toSingleGuide and silently returned the first match (v3).

Refactor parseGuides to walk one Guide per top-level YAML entry:

  - 1 versions: child  -> SingleGuide
  - 2+ versions: child -> GrailsVersionedGuide, with one rendered link
                          per version. The YAML version key is used
                          DIRECTLY as the integer major version, which
                          eliminates BRANCH_TO_MAJOR entirely.

sampleRef.repo is now treated only as the "Get the Code" target on the
rendered chrome - it is never used to identify or group guides. Two
YAML entries that happen to point at the same external repo are still
rendered as two separate guides.

Adds GuidesFetcherSpec with 7 unit tests pinning the regression cases:

  - SingleGuide for 1-version entries
  - GrailsVersionedGuide for 2+-version entries with the YAML version
    key preserved as the int major version (covers the master->4
    overwrite + missing grails7/grails8)
  - Two YAML entries sharing sampleRef.repo render as two guides
    (covers all 4 collision pairs above)
  - Two YAML versions sharing the same branch are both kept when they
    belong to the same guide (covers grails-mock-basics)
  - Future-dated guides are filtered when skipFuture is true
  - Empty versions: blocks are silently skipped
  - Sort order is publication-date-descending

== GuidesPage: trim dead categories, add Web Layer, curate tag cloud ==

categories map: dropped Grails + Android, Grails + Angular,
Grails + AngularJS, Grails + iOS, Grails + RIA. Each had 1-2 stale
guides and was eating equal real estate to Advanced Grails (22 guides).
Their guides remain built and reachable via tags, search, and direct
URL; only the index-page section is gone.

Added Web Layer (5 guides today: htmx, tailwindcss, vite-spa,
fields-custom-widgets-and-wrappers, rest-library). Without this
section, rest-library was the only one of those guides that didn't
even fit in the top-8 Latest Guides sidebar, so it was completely
invisible from the index.

Reshuffled the two-column grid so the modern stacks (Apprentice,
Advanced, Web Layer, DevOps) sit above the older ones (GORM, Testing,
Vue, React, Google Cloud). DevOps in particular was previously buried
under the legacy iOS / Android / RIA cluster despite having more guides
than any of them.

tagCloud: filters out version-label tags (grails3..grails8) - they
artificially dominated the cloud by occurrence count without adding
navigational value (the version is implicit in the guide URL anyway).
Caps the visible set to TAG_CLOUD_LIMIT=50 most-used tags before
re-sorting alphabetically for display, so the long tail of one-shot
legacy tags (apple-tv, tvml, aws-elasticbeanstlak, ...) no longer
clutters the sidebar.

== Verified ==

  ./gradlew :buildSrc:test --tests 'website.model.guides.GuidesFetcherSpec'
    -> all 7 pass

  ./gradlew build validateGuides
    -> BUILD SUCCESSFUL, validateGuides 93 guide(s) parsed, 0 errors

Local build/dist/guides/index.html before-vs-after:
  - multi-module      0 -> 2 hits
  - rest-library      0 -> 2 hits
  - github-actions-cicd                 0 -> 2 hits
  - grails-as-docker-container          0 -> 2 hits
  - grails-mock-basics  1 (v3 only) -> 2 (v3 + v4)
  - creating-your-first-grails-app  2 (v3,v4) -> 3 (v3,v4,v6)
  - rest-hibernate / grails-on-github-actions / grails-multi-project-build:
    each one stops being mis-rendered as the wrong v8 guide

Latest Guides sidebar now contains all 8 new Grails 8 guides
(was 5 of 8: docker-bootbuildimage, htmx, spock-test-tour, tailwindcss,
vite-spa). Tag cloud is now 50 entries (was 200+).

Assisted-by: claude-code:claude-opus-4-7