docs: keep bundle examples self-contained

[AlexanderLanin]

Fixes #778

The documentation examples intentionally use the test BUILD files as their source of truth. The original literalinclude paths remain unchanged; no copied .inc snapshots are introduced.

The public bundle carries those files through a separate data-only docs_bundle child, composed at a private mount path. The docs() macro stages non-document payloads from composed data-only children below the sandboxed Sphinx source tree, so each file label is declared only on its owning child bundle. Data stays attached to the manifest entry that declares it, preserving the per-entry propagation fix from #779.

A source entry composed with a data-only child carries explicit path_check = "off" because sphinx-mounts 0.1.x cannot express a per-file path-check exception for intentionally declared non-document supporting files outside source_dir. Ordinary mounts remain strict (path_check = "error"). Pure data entries only create mounts for document files; BUILD and other supporting payloads remain bundle inputs without exposing neighboring documents.

This is an intentionally narrow compatibility bridge. Upstream issue useblocks/sphinx-mounts#43 tracks a per-mount allowlist for explicitly declared external dependencies. When that is available, this source-entry-level path_check exception can be replaced by the exact declared files.

Regression coverage includes an external Bzlmod consumer that mounts the public bundle and verifies the rendered original literalinclude, plus a sandboxed needs_json build from a subpackage. The Sphinx action remains sandboxed; the consumer test limits local execution to the known local_path_override sourcelink helper workaround.

Checks:

• pre-commit run --files BUILD docs.bzl bzl/bundle_rules.bzl docs/reference/bazel_macros.rst src/tests/docs_bzl/scenarios/bundle_data_provider/BUILD src/tests/docs_bzl/test_external_consumer_bundle_data.py
• bazel build //src/tests/docs_bzl/scenarios/bundle_data_provider:needs_json //:needs_json
• bazel run //:docs
• .venv_docs/bin/python -m pytest -q src/tests/docs_bzl/test_external_consumer_bundle_data.py

[github-actions]

License Check Results

🚀 The license check job ran with the Bazel command:

bazel run --lockfile_mode=error //src:license-check

Status: ⚠️ Needs Review

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[License Check Output]
Extracting Bazel installation...
Starting local Bazel server (8.6.0) and connecting to it...
INFO: Invocation ID: ceb57c5b-be81-47cd-9e52-e3ea32e8b0d1
Computing main repo mapping: 
Loading: 
Loading: 0 packages loaded
Loading: 0 packages loaded
WARNING: Target pattern parsing failed.
ERROR: Skipping '//src:license-check': no such target '//src:license-check': target 'license-check' not declared in package 'src' defined by /home/runner/work/docs-as-code/docs-as-code/src/BUILD
ERROR: no such target '//src:license-check': target 'license-check' not declared in package 'src' defined by /home/runner/work/docs-as-code/docs-as-code/src/BUILD
INFO: Elapsed time: 8.015s
INFO: 0 processes.
ERROR: Build did NOT complete successfully
ERROR: Build failed. Not running target

[github-actions]

Documentation preview for this pull request is available at:
pr-780: https://eclipse-score.github.io/docs-as-code/pr-780/