[REMOTE-2410] Teach oz-platform to fetch live Markdown docs

[warp-agent-staging]

Description

Teach the bundled oz-platform skill to consult current, authoritative documentation before relying on embedded examples:

• document the agent-readable .md variant available for every docs.warp.dev page
• point agents to llms.txt for documentation discovery
• prefer live Markdown docs and installed CLI help for evolving platform behavior
• update the existing CLI and API references to their Markdown variants

Linked Issue

REMOTE-2410

Testing

Testing-exempt category: pure documentation/skill copy. A regression test would only assert the new prose, so validation instead covered the skill content and every cited live source.

• deterministic content check confirmed the .md, llms.txt, CLI help, and prefer-live-source guidance
• git diff --check
• verified llms.txt, computer-use.md, reference/cli.md, and reference/api-and-sdk.md return HTTP 200; all .md pages returned text/markdown
• exact ./script/presubmit formatting/lint gate passed after refreshing from current master; the full integration suite could not complete in this cloud environment because unrelated tests require desktop/runtime services (XDG_RUNTIME_DIR, X11, SSH, and occupied test ports)

Rework changes

• 🚨 Required Linux CI: reran the failed jobs in run 30569027126; Run Linux tests and Check CI results passed on attempt 2, confirming the untouched AddrInUse failure was transient. No oz-platform skill content changed during rework.
• Refreshed the branch from current master through a conflict-free merge. Repository formatting, clippy, clang-format, and WGSL formatting passed; the full local nextest phase remains limited by unrelated cloud desktop/runtime failures already documented above.

Agent Mode

• Warp Agent Mode - This PR was created via Warp's AI Agent Mode

Originating thread: https://warpdev.slack.com/archives/C0A27NDS7FB/p1785372012766299
Oz run: https://oz.staging.warp.dev/runs/019fb402-d71f-7085-9540-9bff0ba2554c

CHANGELOG-NONE

Co-Authored-By: Warp agent@warp.dev
Co-Authored-By: Oz oz-agent@warp.dev