chore(skills): Update linear-project-status skill with more details & context (#21234)

## Summary

Sharpens the `linear-project-status` skill so it's clearly a tool for
**project leads auditing their own projects**, not a performance review
of any individual. The verdict (Green/Yellow/Red) becomes a signal for
the lead to interpret with context the audit can't see (PTO, competing
priorities, work outside Linear) — not a grade.

## Key changes

- **New "Audience and intent" section** up front, making the framing
explicit. Recommendations target the project's process ("add a target
date", "split the milestone"), not people ("X needs to update more").
- **Lead engagement (dim 2b)** reframed around whether the lead is
*finding time to engage* with the project. Recognizes two healthy shapes
— *implementer* (assigned to issues) and *orchestrator* (drives via
updates / comments / milestones). A `warn` is explicitly not a critique.
- **Target date stability (dim 4)** now weighs both push count and
quality of explanation. Well-documented pushes (illness, dependency
slip, scope change) → `warn`; vague or undocumented pushes → `bad`.
Avoids over-penalising a lead who's transparent about slippage.
- **Target date presence/realism (dim 3)** adds an explicit special-case
block for "target date is today or past, project not Completed" — common
enough to deserve direct handling.
- **Milestone health (dim 6)** adds a distinct "tracking-hygiene gap"
verdict for past-due milestones where the work clearly shipped but
wasn't marked complete. The recommendation is cleanup, not a delivery
concern.
- **Status update cadence (dim 1)** now reads trajectory across the last
~6 weeks. Long silence followed by a fresh update → `warn` framed
positively (the lead has already corrected course). Steady recent rhythm
→ `ok` even if there was an old gap further back. Don't dwell on distant
history.
- **Scope stability (dim 7)** carves out planned decomposition
explicitly: when new issues share a common `parentId`, that's a
structural breakdown of existing scope (healthy), not drift — never flag
it.
- **"Reviewing people instead of the project"** added as the top entry
in the common failure modes list.

## Validation

Iterated against two real Sentry projects ([Hono
SDK](https://linear.app/getsentry/project/hono-sdk-javascript-4117ec2adb5f)
and [Multi-Runtime Server
Integrations](https://linear.app/getsentry/project/multi-runtime-server-integrations-javascript-94fdc006d64e))
— each pass surfaced specific phrasings or rules that needed adjustment,
which are now folded in.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: mydea