feat: agent distribution — llms.txt, llms-full.txt, skill installer

[arhangel66]

Summary

Implements Phase 1 of DAH Agent-First Initial Skill Setup (the lium-skill repo side). After this lands + lium.io redirects, agents will have one-liners for both CLI and skill installation, plus standard llms.txt / llms-full.txt AI-discovery files.

Files

• llms.txt — short index (~20 lines, per llms.txt standard); points to llms-full.txt, SKILL.md, references, install scripts.
• llms-full.txt — self-contained reference (~1088 lines) generated by inlining lium/SKILL.md (minus frontmatter & "Detailed References" section) + lium/references/cli-commands.md + lium/references/sdk-reference.md. Single source of truth stays in SKILL.md + references — no manual dupe.
• scripts/build-llms-full.sh — regenerates llms-full.txt from sources. Run locally or in CI on every push to main.
• agents/install.sh — skill installer (~90 lines), modeled after basilica's. Flags: --claude-only, --cursor-only, --codex-only (default: all three). Depends only on curl. Installs to ~/.claude/skills/lium/, ~/.cursor/skills/lium/, ~/.codex/skills/lium/.
• lium/SKILL.md — replaced relative references/*.md links with absolute GitHub raw URLs (works immediately, independent of lium.io redirects). Also fixed the stale http://16.171.54.255/lium/install.sh → https://raw.githubusercontent.com/Datura-ai/lium/main/scripts/install.sh until the lium.io redirect lands.

What's NOT in this PR

• lium.io redirect rules (/install.sh, /agents/install.sh, /llms.txt, /llms-full.txt → GitHub raw) — belongs to the frontend repo, separate PR.
• Binary CLI install.sh lives in Datura-ai/lium (already exists), not here.
• SDK link on lium.io homepage — frontend task.

Post-merge (after lium.io redirects)

Can switch SKILL.md links back to the shorter https://lium.io/... variants.

Test plan

• bash -n both scripts — syntax OK
• ./scripts/build-llms-full.sh writes llms-full.txt (1088 lines, correct section boundaries)
• HOME=<tmp> ./agents/install.sh --claude-only — downloads SKILL.md + both references into $HOME/.claude/skills/lium/ with correct layout
• After merge, curl -fsSL https://raw.githubusercontent.com/Datura-ai/lium-skill/main/agents/install.sh | bash end-to-end from a clean machine
• After merge, verify https://raw.githubusercontent.com/Datura-ai/lium-skill/main/llms.txt and .../llms-full.txt are fetchable

[arhangel66]

Addressed review in 844c506. Summary of fixes:

• feat: agent distribution — llms.txt, llms-full.txt, skill installer #1 llms.txt → lium.io URLs — left as-is per discussion (short domain is the long-term entry point; 404 until frontend PR lium-io-frontend#174 is deployed is expected).
• Install via skills.sh and pre-approve lium bash calls #2 --help under curl | bash — replaced sed "$0" with an inline usage() function. Verified via bash -c "$(cat agents/install.sh)" bash --help — prints correctly without touching $0.
• DAH-2587: document agent-native signup in the lium skill #3 version pinning — added LIUM_SKILL_VERSION env var (default main). Override to pin: LIUM_SKILL_VERSION=v0.1.0 curl ... | bash. LIUM_SKILL_RAW_BASE still available for full URL override.
• DAH-2592: describe the real lium CLI in the agent skill #5 awk scope bug in build script — strip_detailed_references_section now stops skipping at the next ^## heading, so appending sections after ## Detailed References no longer truncates them.
• DAH-2587: link the agent guide from llms.txt #6 silent overwrite — existing files now get copied to *.bak before overwrite. Added --force flag to opt out. Verified by installing → editing SKILL.md → re-installing → SKILL.md.bak contains the edit.
• #7 offline readability — SKILL.md kept the relative [references/...](references/...) links and appended the raw GitHub URL as a fallback, so both offline (local file) and online (remote fetch) agents resolve them.
• Sync the skill with the shipped CLI (v0.0.27) #4 CI drift check — added .github/workflows/check-llms-full.yml that regenerates llms-full.txt and fails on diff. Triggers on PRs touching SKILL.md, references/**, build-llms-full.sh, or llms-full.txt itself, and on push to main.