Remove the landing page and the docs site

[SaladDay]

Documentation lives only in the repository Markdown, which readers use on GitHub. This PR deletes the landing page (site/) and the Fumadocs docs site (apps/docs), along with everything that existed only for them:

• the root dev:docs, build:docs and check:docs scripts;
• the pnpm workspace entry, plus the lockfile importer and the packages only it used;
• the check-docs Makefile target and its step in make check;
• the name-guard rules for the removed paths;
• the ignore entries;
• the site/ copy in scripts/build-core-distribution.sh.

In Markdown, only links to deleted files were changed. The docs overhaul PRs remove the prose that still describes the docs site.

Guards kept after the site scripts were removed

• Routes and contracts: services/core/internal/api/contract_routes_test.go walks the chi router the server mounts, with every option-gated route group enabled. It compares the router in both directions with openapi.yaml (/v1), core.openapi.yaml (/core/v1) and runtime.openapi.yaml (/api/v1), matching path parameter names exactly. It also checks that every contract path starts with its namespace prefix.
  • Exclusions are keyed by method and path: GET /healthz, HEAD/OPTIONS methodNotAllowed guards, and the native-installer download tree /api/v1/agent-daemon/install/*.
  • An exclusion that matches no registered route fails the test.
• Markdown links: test_repository_markdown_links_resolve checks relative links and anchors in every tracked *.md outside example/ and provenance/. It reuses the bundled-docs checker in scripts/core-distribution-manifest.py. Three links that were split across two lines were rejoined; no words changed.
• Dropped on purpose: the docs-site phrase checks and the retired-claims list. None of the retired phrases appears in the repository today.

Verification

Only the checks for what this PR touches ran, per the focused-check rule. All passed:

• go test ./services/core/internal/api -run '^TestContractsPublishExactlyTheRegisteredCoreAndMachineRoutes$'
• python3 scripts/core-distribution-manifest.test.py (19 tests)
• python3 scripts/check-names.py
• pnpm install --frozen-lockfile and pnpm typecheck
• make -n check
• bash -n scripts/build-core-distribution.sh

A full gate started earlier on the same change was stopped partway. Before the stop, make check (without browser cases), pnpm typecheck, test:core-doctor and test:web had passed.

Review

A fresh Claude subagent blind-reviewed the full diff. It was given only the requirements, the boundaries, the checkout and the baseline.

• P0/P1: none.
• P2: the dropped retired-claims check. It is intended, as noted above.
• P3: three small findings: exact /v1 parameter names, method-keyed exclusions that must match a route, and a non-empty file list for the link test. All three were fixed in c127e4bb and verified with the focused tests, without another review round.

example/** is untouched.

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