docs: polish first release documentation

[timzsu]

Purpose

Complete the documentation and package-polish portion of the first-release roadmap, with manual non-code alignment against FlowMesh's released repository shape.

Changes

• Rewrite README as a concise public quick start with FlowMesh-style badges and links to deeper docs.
• Add reference docs for environment variables, CLI commands, API routes, architecture, SDK usage, workflow formats, operation classes, and hooks/plugins.
• Rename docs to the FlowMesh convention: API.md, ARCHITECTURE.md, CLI.md, ENV.md, and PLUGINS.md.
• Convert AGENTS.md to a pointer-first FlowMesh-style routing doc that points contributors and agents to focused docs while retaining high-signal safety rules.
• Align issue templates with the FlowMesh template structure, including a shorter RFC template.
• Rename the unit-test workflow to match FlowMesh's non-code workflow naming and update contributing docs.
• Pin FlowMesh packages to 0.1.1 and refresh uv.lock.
• Remove stale requirements-sync documentation and the permanent legacy env-key denylist.
• Add PyPI package metadata and include docs in the source distribution via MANIFEST.in.
• Fix SDK/API drift: info.status() now uses /healthz, the stale job logs SDK method is removed, and jobs.wait() uses the server's lowercase terminal states.
• Correct CLI and quick-start examples for YAML format, required inputs, required output prefix, artifact output, and workflow-file help text.

Design

Keep README focused on install, quick start, and navigation. Put detailed reference material under docs/ so the PyPI long description remains readable while users still have discoverable public docs in the repository. Keep issue templates, workflow names, and doc names close to FlowMesh so the two OSS repositories are easier to maintain together.

Test Plan

• uv run pytest tests/ --ignore=tests/server -q
• uv run --no-sync pre-commit run --all-files
• uv run scripts/dev/check_env_examples.py
• uv lock --check
• uv build --out-dir dist
• uv run --no-sync scripts/ci/check_package_build.py --dist dist
• markdown local-link check
• referenced repository path check
• CLI help checks for lumilake, deploy, job, job submit, job preview, job artifact, worker, and trace

Test Result

All listed checks passed.

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Pre-submission Checklist

• I have read CONTRIBUTING.md.
• I have run uv run pre-commit run --all-files and fixed any issues.
• I have added or updated tests covering my changes (if applicable).
• I have verified that uv run pytest tests/ --ignore=tests/server passes locally.
• If I changed the SDK or CLI, I have verified the affected interface works locally.
• If this is a breaking change, I have prefixed the PR title with [BREAKING] and described migration steps above.
• I have updated documentation or config examples if user-facing behavior changed.