feat: add diagnosing-superpowers skill

Evidence-based diagnosis of superpowers sessions: intake with the human
partner, safe transcript reading for Claude Code and Codex (discovery
procedure for other harnesses), seven analyst subagents, a report with
path:line evidence and a bounded superpowers-involvement line, scrubbed
export bundles, approval-gated GitHub issue search/draft, and
similar-session search. Includes spec, plan, structure test, and README
and docs index lines.

Developed RED-GREEN-REFACTOR per writing-skills: 46 scored scenario runs
across five SKILL.md versions, all twelve scenarios clean against the
final version, micro-tests control 5/5 to skill 0/5 on both
baseline-failing prohibitions, and one end-to-end run. Eval records are
kept by the maintainer outside the repo.

Claude-Session: https://claude.ai/code/session_01DyaGKhTXvHNs2JgPhDktz7

skills/diagnosing-superpowers/templates/bundle-README.md

@@ -0,0 +1,44 @@
+# Superpowers session diagnosis bundle
+
+Session: <session-id>
+Harness: <name> <version>    Superpowers: <version> (<sha or "not a checkout">)
+Redaction level: skeleton | evidence | full
+Built: <ISO timestamp>
+
+## What this is
+
+A scrubbed record of a coding-agent session in which superpowers was
+installed and something went wrong, prepared so that an agent or person
+who was not present can decide whether superpowers contributed and, if so,
+what to change. The report inside states what happened with `path:line`
+evidence. By design it contains no diagnosis of superpowers and no proposed
+fix; that is the reader's job.
+
+## Files
+
+- `report.md` — the diagnosis report (problem statement, verdict,
+  environment, sessions, timeline, findings, involvement, coverage notes).
+- `case.md` — the case file the analysts worked from.
+- `environment.json` — machine-readable copy of the environment section.
+- `timeline.md` — the per-turn timeline.
+- `findings/<dimension>.md` — raw analyst findings per dimension.
+- `transcripts/<session-id>.md` — condensed per-turn rendering of each
+  examined session (never the raw JSONL). At *skeleton* level tool-result
+  bodies are replaced by `[tool result: <tool>, <bytes> bytes, exit <code>]`;
+  at *evidence* level bodies are kept only for events cited in findings; at
+  *full* level all bodies are kept.
+- `scrub-log.md` — every placeholder used and its category (never the
+  original value).
+
+## How to read it
+
+Start with `report.md` §1–2, then §7 (involvement) and the evidence lines
+it cites, then the matching turns in `transcripts/`. `path:line` references
+point at the original files on the reporter's machine; the same line
+numbers are preserved in the condensed transcripts as `[L<n>]` markers.
+
+## Redaction
+
+Placeholders look like `<EMAIL-1>`, `<PERSON-2>`, `<SECRET-3>`, `<HOST-4>`,
+`<REPO-5>`, `<ORG-6>`, `<PROPRIETARY-7>`; home paths are rewritten to `~/…`. The same placeholder
+always refers to the same original value within this bundle.