[soareschen]

This PR changes only the README, the agent guidance, and the repository's local agent configuration.
The README and AGENTS.md now describe this tree as the v0.8.0 release and do not mention the
pre-release crates. AGENTS.md now names point-first-writing as the prose skill, in place of
dual-reader-prose. The PR also deletes the .claude directory, so the repository does not ship
any skill or harness setting. The PR does not change any source, test, or manifest file, so it does
not affect the build or the test suite.

Name the official versions only

The knowledge base's
rule on versions
says that a document names official releases only. A pre-release on crates.io is a test run of the
release process, and documents do not track it. Before this change, the README told readers to
depend on the git main branch, and AGENTS.md named the pre-release version as the current one.
Both files now describe the tree as v0.8.0, as if that release were already published, so they will
not need an edit when it ships.

The README changes remove each mention of the pre-release:

• Version notice: It states that the repository describes v0.8.0, which is not compatible with
  v0.7.0, and it does not name the pre-release crates.
• Install note: The PR removes the note that told readers to depend on the git main branch.
• cargo-cgp: The Nix command uses the v0.1.0 flake tag, and the text calls cargo-cgp "an
  early release".
• Project status: The status does not call v0.8.0 a pre-release.

The AGENTS.md changes tell agents how to treat the pre-release version:

• Project status: A manifest can carry a pre-release suffix such as 0.8.0-alpha, but every
  document, comment, and README must describe the tree as v0.8.0. The section links to the
  knowledge-base rule and applies it to cargo-cgp v0.1.0 too. It calls v0.7.0 "the previous
  official release", not "the stable release on crates.io".
• Conventions: The lockstep-version bullet names the release in preparation, 0.8.0, instead of
  the suffix the manifests carry now.

The workspace manifests still declare 0.8.0-alpha. The rule applies to documents and not to code,
so this PR leaves the manifests unchanged.

Adopt point-first-writing and remove .claude

The "Orient before any task" section of AGENTS.md now tells agents to load /point-first-writing
when they edit Markdown or inline comments. That skill is the prose convention that cargo-cgp and
the knowledge base already require. The knowledge base publishes it in its
skills/ directory, and
the /cgp skill comes from cgp-skills. A
contributor installs both skills where their agent harness loads skills from.

The PR deletes every file under .claude:

• .claude/skills/dual-reader-prose/SKILL.md: the bundled copy of the prose skill that
  point-first-writing replaces.
• .claude/skills/cgp: a symlink into a sibling cgp-skills checkout, which worked only in the
  author's directory layout.
• .claude/settings.local.json: three Bash permissions with paths from one machine.