docs: product noun Issue; freeze wire at ur.*/UR-NNN

[rawphp]

Summary

• Product noun Issue in high-signal agent docs (aligned with do-work.io UI / issues tables).
• Wire frozen: MCP ur.* / ur_*, param ur, slug UR-NNN, port ops create_ur / read_ur / … — no issue.create / ISSUE-NNN cutover.
• agents/tracker/do-work-io.md: hierarchy → issues / issue_artifacts + explicit naming table.
• Linear disambiguation: do-work Issue = Project Milestone; Linear Issue = REQ.
• Field lesson §29: don’t invent capability names from product noun.

Scope (intentionally partial)

• High-signal surfaces + do-work-io integration reworded.
• Dense mid-body “UR” shorthand remains in status/verify/go/markdown/sqlite/linear agents.
• Markdown paths still .do-work/user-requests/.

Base

PR base is base/skill-monorepo-pin (f4e5fe5, the do-work.io monorepo submodule pin) so this review is one commit only. Merge to main separately if/when the do-work-io tracker stack lands on main.

Test plan

• Read agents/tracker/do-work-io.md “Product naming vs wire” — Issue noun, wire still ur.create / ur_create
• Confirm no agent doc invents issue.create as the live tool name
• Symlink path still resolves: ~/.grok/skills/do-work → this tree