docs(invocation-mode): grade the six ungraded human-only skills against the exception classes #7974

Refs: #6458

Agent Brief

Type: Task
Summary: Add a dated grade of the six non-setup disable-model-invocation: true skills that the invocation-mode rubric never graded, each with its exception class or a flip verdict.

Current behavior:
The invocation-mode rubric's fleet grade (2026-08-17) covers 10 non-setup human-only skills. Six later ones carry true with no recorded class: discipline:be-ambitious, docs-naming:generate-file-name-gate, playbooks:repo-sweep, repo-fleet-hygiene:sync, session-flow:tidy-work, testing:map-features. The owner's 2026-10-05 direction on #6458 is model-invocable by default.

Desired behavior:

• The rubric gains a dated grade section with one row per skill: the exception class it meets (i, ii or iii, as the rubric defines them) with the evidence from that skill's own body (a side effect without its own confirmation gate, a human-internal trigger, maintainer-only use), or FLIP -> false when none applies.
• A row whose skill has a destructive or mutating step that already asks for approval is graded FLIP, per the 2026-10-05 direction, and says so.
• No skill frontmatter changes in this item.

Key interfaces:

• The invocation-mode rubric's exception classes and fleet-grade table format.

Acceptance criteria:

• The rubric has a new dated grade section listing exactly the six skills named above.
• Each row names a class with a quoted line from that skill's SKILL.md, or a FLIP verdict with the reason no class applies.
• The diff changes no SKILL.md.

Out of scope:

• The 64 setup skills and the nine skills graded KEEP on 2026-08-17 (owner-decision siblings).
• Flipping any skill (sibling item).
• Description trimming and skillListingBudgetFraction.

This was generated by AI during backlog shaping. Split from #6458; the owner approved filing it in an attended backlog-shaping session on 2026-10-18.