Support remote project skills

[moirahuang]

Description

• Add remote project skill discovery from remote repository metadata and hydrate SKILL.md contents through daemon-backed file reads.
• Preserve host-aware skill identity with LocalOrRemotePath across parsing, lookup, output rendering, and editor-open flows.
• This is the lower PR in the stack; remote project rules build on top in Support remote project rules #11460.

Linked Issue

• The linked issue is labeled ready-to-spec or ready-to-implement.
• Where appropriate, screenshots or a short video of the implementation are included below (especially for user-visible or UI changes).

Testing

• cargo check --manifest-path /Users/moirahuang/.warp-dev/worktrees/warp/moira/skills/Cargo.toml -p warp --message-format short
• cargo test --manifest-path /Users/moirahuang/.warp-dev/worktrees/warp/moira/skills/Cargo.toml -p ai skills --lib --message-format short
• I have manually tested my changes locally with ./script/run

Screenshots / Videos

Not included in this draft submission.

Agent Mode

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

Agent Artifacts

• Conversation: https://staging.warp.dev/conversation/00d0c857-cf4a-4191-8bc7-bb8054fa1105
• Plan: https://staging.warp.dev/drive/notebook/v1fYGOG4E4tKWrmbRgBne1

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

[moirahuang]

• Support remote project rules #11460
• Support remote project skills #11459 👈 (View in Graphite)
• master

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