docs(zarr-metadata): docs-site polish: repo link, titles, RTD build skips, branding (#4210)

* docs(zarr-metadata): point the site's repo link at the package directory

The material header source widget linked to the zarr-python repository
root, presenting the site as zarr-python's. Link the package directory
and label it zarr-python/packages/zarr-metadata instead. edit_uri
becomes absolute because mkdocs would append it to repo_url's subpath.

Assisted-by: ClaudeCode:claude-fable-5

* docs(zarr-metadata): drop redundant frontmatter title on the homepage

Material appends the site name to explicit frontmatter titles, so the
homepage browser title rendered as 'zarr-metadata - zarr-metadata'.
Without the frontmatter it falls back to the site name alone.

Assisted-by: ClaudeCode:claude-fable-5

* docs(zarr-metadata): skip unrelated RTD PR builds; add site logo and favicon

Both Read the Docs projects rebuilt on every pull request regardless of
what changed. Each config now cancels PR builds via exit code 183 when
the diff against origin/main does not touch its half of the repo:
the zarr-metadata project skips PRs that leave packages/zarr-metadata
untouched, and the zarr-python project skips PRs confined to it. Scoped
to external versions because origin/main is only a meaningful diff base
for PR builds.

The package site also gets the zarr logo and favicon, copied from the
zarr-python docs, instead of stock Material icons.

Assisted-by: ClaudeCode:claude-fable-5

* fix(docs): quote-free exclude pathspec in RTD build-skip rule

Read the Docs strips shell quoting from build commands, so the quoted
':(exclude)packages/zarr-metadata' pathspec reached /bin/sh unquoted and
the bare parenthesis was a syntax error, failing every zarr PR build.
Use git's quote-free :! exclude form, which survives the stripping;
reproduced the mangling and verified both forms against dash locally.

Assisted-by: ClaudeCode:claude-fable-5

Author: d-v-b

.readthedocs.yaml

@@ -5,6 +5,19 @@ build:
   tools:
     python: "3.12"
   jobs:
+    post_checkout:
+      # Cancel pull request builds whose changes are confined to the
+      # zarr-metadata package, which has its own Read the Docs project. Exit
+      # code 183 cancels the build and reports success to the Git provider.
+      # Scoped to PR builds ("external" versions) because origin/main is only
+      # a meaningful diff base there. Read the Docs strips shell quoting from
+      # commands, so the exclude pathspec must use the quote-free :! form,
+      # not ':(exclude)'.
+      - |
+        if [ "$READTHEDOCS_VERSION_TYPE" = "external" ] && git diff --quiet origin/main -- :!packages/zarr-metadata;
+        then
+          exit 183;
+        fi
     install:
       - pip install --upgrade pip
       - pip install .[remote] --group docs

packages/zarr-metadata/.readthedocs.yaml

@@ -9,6 +9,16 @@ build:
   tools:
     python: "3.12"
   jobs:
+    post_checkout:
+      # Cancel pull request builds that do not touch this package. Exit code
+      # 183 cancels the build and reports success to the Git provider. Scoped
+      # to PR builds ("external" versions) because origin/main is only a
+      # meaningful diff base there.
+      - |
+        if [ "$READTHEDOCS_VERSION_TYPE" = "external" ] && git diff --quiet origin/main -- packages/zarr-metadata;
+        then
+          exit 183;
+        fi
     install:
       - pip install --upgrade pip
       - pip install ./packages/zarr-metadata --group packages/zarr-metadata/pyproject.toml:docs

packages/zarr-metadata/docs/_static/favicon-96x96.png

@@ -1,7 +1,3 @@
----
-title: zarr-metadata
----
-
 # zarr-metadata
 
 Basic tools for modelling Zarr metadata, with minimal dependencies.

packages/zarr-metadata/docs/_static/logo_bw.png

@@ -1,7 +1,10 @@
 site_name: zarr-metadata
-repo_name: zarr-developers/zarr-python
-repo_url: https://github.com/zarr-developers/zarr-python
-edit_uri: edit/main/packages/zarr-metadata/docs/
+# The package lives in the zarr-python monorepo; point the header source
+# widget at the package directory rather than the repository root.
+repo_name: zarr-python/packages/zarr-metadata
+repo_url: https://github.com/zarr-developers/zarr-python/tree/main/packages/zarr-metadata
+# Absolute because mkdocs would otherwise append this to repo_url's subpath.
+edit_uri: https://github.com/zarr-developers/zarr-python/edit/main/packages/zarr-metadata/docs/
 site_description: Spec-defined metadata types, models, and validators for Zarr v2 and v3.
 site_author: Davis Bennett
 site_url: !ENV [READTHEDOCS_CANONICAL_URL, 'https://zarr-metadata.readthedocs.io/']
@@ -29,6 +32,8 @@ watch:
 theme:
   language: en
   name: material
+  logo: _static/logo_bw.png
+  favicon: _static/favicon-96x96.png
 
   palette:
     # Light mode