docs: reflect the shipped 0.1.0 release in adoption docs

[justinmclean]

Summary

0.1.0 is released (promoted to dist/release/magpie/0.1.0), so the adoption docs no longer match reality:

• README + install-recipes: svn-zip is the recommended production path rather than "forthcoming"; git-branch is no longer "the default during the framework's pre-release phase".
• install-recipes Method 1 fetched apache-magpie--source-release.zip, which is not the artefact name that shipped. Every other doc in the tree says -source.zip, so the recipe as written 404s.
• install-recipes Method 1 templated a adopter dist subdirectory. Magpie has its own dist area now, so hard-code it and split DIST_BASE (KEYS at the project root) from REL_BASE (artefacts under the per-version subdirectory).
• README cross-reference still called MISSION.md a draft proposal; it was adopted by Board resolution on 17 June 2026, and the NOTE block earlier in the README already says so.

Type of change

• Skill change (.claude/skills/<name>/) — eval fixtures updated below
• Tool / bridge contract (tools/<system>/*.md)
• Python package (tools/*/ with pyproject.toml)
• Groovy reference impl
• Cross-cutting (RFC, AGENTS.md, sandbox, privacy-LLM)
• Documentation (docs/, README.md, CONTRIBUTING.md)
• Project template (projects/_template/)
• CI / dev loop (prek, workflows, validators)
• Other:

Test plan

• prek run --all-files passes
• For Python packages touched: uv run pytest / ruff check / mypy passes
• For Groovy bridges touched: command-line invocation tested end-to-end
• For skill changes: eval suite passes for the affected skill
  (PYTHONPATH=tools/skill-evals/src python3 -m skill_evals.runner tools/skill-evals/evals/<skill>/)
• For skill behaviour changes: a new or updated eval fixture is included in this PR
  (a regression test for the bug fixed / the behaviour added — see CONTRIBUTING.md)
• Other: