docs: remove maintainer-only content, duplicates and unbacked claims

[kannandreams]

A review of everything user-facing in the repository, with three goals: remove content that only the maintainer needs, remove filler, and remove claims that the code does not back.

Removed from the repository

• capabilities/agent-forge/ (37 files) — a vendored AI-agent skill library. Maintainer tooling; it lives in its own repository.
• ROADMAP.md, TASKS.md, SPEC.md, DECISIONS.md — internal planning scaffolds. TASKS.md and SPEC.md had unclosed code fences; ROADMAP.md proposed glyf serve as future work. The two ADRs in DECISIONS.md now live in ARCHITECTURE.md.
• docs/ — an older, diverged copy of the docs-site guides. The README table now links the docs-site sources on GitHub, so the guides stay reachable before the site opens. Four sentences that existed only in docs/ were carried across.
• docs/release.md and the rulesets how-to — maintainer procedure, relocated out of the public repo.
• The three blog posts — each was a few sentences of the same thesis with no commands or output; the blog is unlinked until there is a post with content.
• examples/screenshots.md — an asset-capture checklist.

Claims corrected

• toolbar.actions was documented with a "show only one action" example. The loader validates the key but toolbar.j2 never reads it, so the example did nothing. Removed from the docs and from the example dashboards. (The key is still accepted, so existing YAML keeps working — worth a follow-up to either wire it or drop it.)
• npm install @glyf/client @glyf/react and the GlyfProvider example — these packages do not exist. The page now documents the real bundle.json contract and points the JavaScript packages at the roadmap.
• activation_health(0.82) in the product-analytics page raises TypeError (the macro's parameters are keyword-only). The page now shows the shipped product.yml.
• Roadmap listed serve, interactive charts and the Looker guide as planned; all three ship.
• CONTRIBUTING.md promised "an active discussion thread every month"; there has been one welcome thread since May.
• ARCHITECTURE.md described theme files and a token JSON that do not exist.

Consolidated

• guides/configuration → reference/configuration (one page, now also documenting execution.backend and that render.formats accepts only svg/png).
• get-started/existing-dbt-project → get-started/quickstart (70% identical).
• Three AI-context pages → one, stating the validation commands once instead of four times.
• The macro chapter was in both the dashboard YAML and macros guides; the YAML guide now points at the macros guide, which also un-nests "Custom macros" from under "Theme".
• llms.txt rewritten: its "core workflow" omitted glyf build and glyf serve.

Checks

• npm run build in docs-site/ passes with onBrokenLinks: 'throw'.
• uv run pytest: 115 passed.