feat(skills): extension-runtime-and-packaging skill, snippet and example

[TMHSDigital]

Closes #380.

What ships

• Skill extension-runtime-and-packaging covers what breaks an extension after its first run:
  • bundled wheels instead of pip;
  • user data in extension_path_user instead of beside __file__;
  • the network permission plus bpy.app.online_access;
  • bl_ext.<repo>.<id> package names;
  • blender --command extension validate / build / server-generate in CI.
• Snippet snippets/extension-user-data.py: a settings file in the extension's user directory, plus an online_access guard.
• Check-only example examples/extension-package-lifecycle: builds, lists, installs, upgrades (0.1.0 → 0.2.0) and removes the repo's extension template. Every step runs in a throwaway BLENDER_USER_RESOURCES. Falsifiers: --validate-only (exit 4) and --data-next-to-file (exit 7).
• Wiring: catalog row; examples/skills.json entry (→ this skill and headless-batch-scripting); Cursor manifest; counts (17 skills, 28 snippets, 65 examples, 9 check-only).
• Generator fix: build_examples_index.py now unquotes a stripped link whose text is a path. This example's README lead made check_skill_refs fail on a bare templates/... path in the generated section.

Measured facts the skill relies on

All on local 4.5.11 LTS, 5.1.2 and 5.2.1 LTS, unless a row says otherwise:

Fact	Result
validate / build with a wheels entry whose file is missing	0 / 1 (no zip) on all three: validate is not a release gate
validate with platforms = ["win64"], or schema_version = "9.9.9"	0 (4.5.11 and 5.2.1)
validate with no id, version = "one", type = "plugin", permission teleport, blender_version_min = "4"	1 (4.5.11 and 5.2.1)
Installed __package__	bl_ext.user_default.example_addon
extension_path_user(__package__)	extensions/.user/user_default/example_addon, beside the install tree
extension_path_user("probe_ext") (a bare name)	ValueError: The "package" does not name an extension (4.5.11 and 5.2.1)
Upgrade 0.1.0 → 0.2.0	Install tree replaced (a file written beside __file__ is gone); user data kept
extension remove	Deletes the user directory too
Bundled wheel (hand-built py3-none-any)	Lands in extensions/.local/lib/python3.11/site-packages (4.5.11) or python3.13 (5.2.1), already on sys.path
bpy.app.online_access	False by default, True under --online-mode

Evidence

Live run: tests/smoke/run_catalog.py over the new row; all PASS.

Binary reports	Happy path	--validate-only	--data-next-to-file
Blender 4.5.11 LTS	PASS	PASS (exit 4)	PASS (exit 7)
Blender 5.1.2	PASS	PASS (exit 4)	PASS (exit 7)
Blender 5.2.1 LTS	PASS	PASS (exit 4)	PASS (exit 7)

Local checks: tests/run_all.py 31 passed, 0 failed (counts, frontmatter, skill refs, examples index, exit-code README, catalog).

Inspection only:

• The pip download … --python-version 3.11 --platform win_amd64 line follows the Blender manual's wheels page; it was not run here.
• --split-platforms is described from extension build --help and the manual; it was not run.

The example starts about a dozen child Blenders, so expect it to be one of the slower smoke rows.

🤖 Generated with Claude Code

[TMHSDigital]

CI evidence before merge: all checks pass ( 13 pass ). Blender Smoke on PR head: Blender 5.2.2 LTS / Blender 4.5.14 LTS. Summaries (happy path; falsifiers) per leg: 144 passed, 1 skipped, 0 failed;164 passed, 0 skipped, 0 failed;142 passed, 3 skipped, 0 failed;149 passed, 15 skipped, 0 failed;