content: fix version-fact errors across rules, skills, snippets and the add-on template

[TMHSDigital]

Why it matters

This repo's value is that AI assistants can trust its version facts. Each item below is small, but each one teaches a wrong version boundary or a stale "current" label, and the AI repeats it confidently.

Evidence

#	Location	Problem
1	rules/prefer-temp-override-over-context-copy.mdc:3 and :15-17	Says the context-dict pattern was "deprecated in 4.x and … removed in 5.x". Passing a context dict to an operator was removed in 4.0 (deprecated 3.2–3.6), so it already fails on the 4.5 LTS fallback. The rule understates the breakage.
2	skills/procedural-materials-and-shaders/SKILL.md:163	Dates the Principled BSDF Specular → Specular IOR Level rename to 5.0. It came with the Principled v2 rewrite in 4.0.
3	skills/bl-info-migration/SKILL.md:23,223, skills/drivers-and-app-handlers/SKILL.md:272, skills/procedural-materials-and-shaders/SKILL.md:161, skills/addon-scaffolding/SKILL.md:202	Version tables and prose still call 5.1 "stable". The repo targets 5.2 LTS as current stable and 5.1 as prior stable.
4	skills/bl-info-migration/SKILL.md:225	Calls bl_info the "primary path" on 4.5. From 4.2 on, Extensions is primary and bl_info is legacy.
5	skills/vse-python/SKILL.md:155	Links bpy.types.Sequence under api/current/. On 5.x the type is Strip, so the link is dead.
6	skills/vse-python/SKILL.md:41	Says "Branch on bpy.app.version" and then "Always branch on hasattr". Pick one and explain when the other applies.
7	snippets/action-ensure-channelbag-for-slot.py:11	The comment ends with Import path (5.0+): and nothing follows it.
8	templates/extension-addon-template/blender_manifest.toml	maintainer is a contact@example.com placeholder. license = ["SPDX:MIT"] validates, but extensions.blender.org requires GPL-3.0-or-later for add-ons with code. A template framed as submission-ready should default to that or say why it doesn't.

Suggested approach

One PR that fixes each row. For rows 1–2, cite the relevant Blender release-notes page in the corrected text. For row 3, consider a single "version policy" line that skills link to, instead of per-skill "stable" labels that go stale with every release.

Done when

• All 8 rows are fixed or explicitly waived in the PR body.
• grep -rn "5.1 stable\|5.1 (stable)" skills/ returns nothing.