docs: revamp README as storefront for docs site

[danielmeppiel]

Summary

Now that the docs site is live at microsoft.github.io/apm/, the README no longer needs to serve as both landing page AND reference manual.

This PR revamps the README following the uv pattern (benchmarked against uv, ruff, deno, bun) — enough content to convey the value proposition without clicking away, but funneling to the docs site for everything else.

What changed

Section	Before	After
Badges	4 shield badges	Removed
Tagline	Compliance line + expanded description	Compliance line preserved (standalone)
Agent list	Copilot · Cursor · Claude · Codex · Gemini	Copilot · Claude Code (currently supported)
Doc links	Bottom table with relative docs/ paths	Prominent top bar linking to docs site
Why APM	2 paragraphs	Condensed to 1 paragraph
apm.yml example	10 deps with verbose comments	4 deps, cleaner
Primitives table	7-row feature matrix	Replaced by single "Highlights" bullet list
Install	2-step numbered + separate "Install From Anywhere" section	Single curl + collapsible alternatives
Create & Share	Full scaffold + heredoc example	Removed (covered in docs)
Key Commands	7-row command table	Removed (covered in CLI Reference doc)
Configuration	Token table + link	Removed (covered in docs)
APM Packages	Description + 3-row popular sources table	Removed (covered in docs)
Documentation table	3-row link matrix	Removed (replaced by top bar links)
Community	Scattered links	Consolidated section
Open standards	Kept	Kept
Trademarks	Kept	Kept

250 lines → ~80 lines

Constraints respected

• **An open-source, community-driven dependency manager for AI agents.** kept verbatim (Microsoft compliance)
• All deep content lives in the docs site, not lost

[Copilot]

Pull request overview

This PR refactors README.md to act as a lightweight “storefront” that points users to the hosted documentation site, rather than duplicating reference content in the repo README.

Changes:

• Replaces the long-form README content with a shorter value proposition + highlights section.
• Adds prominent links to the docs site (Docs / Quick Start / CLI Reference).
• Simplifies examples and installation instructions, removing detailed reference sections now covered by the docs.

Comments suppressed due to low confidence (1)

README.md:43

• This line implies apm compile outputs AGENTS.md specifically for GitHub Copilot, but the documentation states AGENTS.md is also consumed by other agents/tools (e.g., Cursor/Codex, and generally the AGENTS.md standard). Consider broadening the parenthetical or rewording it to avoid narrowing the compatibility story compared to the docs site.

- **Compile to standards** — `apm compile` produces `AGENTS.md` (GitHub Copilot) and `CLAUDE.md` (Claude Code)

[Copilot]

apm pack is described as producing a "zipped" package, but the docs describe apm pack --archive as producing a .tar.gz archive (and without --archive it outputs a directory bundle). To avoid misleading users, consider rephrasing this as "portable bundle" / ".tar.gz archive" and/or mention the --archive flag.

Suggested change

	- **Create & share** — `apm pack` bundles your current configuration as a zipped package
	- **Create & share** — `apm pack` bundles your current configuration as a portable bundle (directory by default, or `.tar.gz` archive with `--archive`)