fix: per-entity Step 0.55, LAW 7 sub-run quiet, default 2, canonical SKILL.md (#311)

Four fixes based on 2026-04-22 test-window feedback on v3.0.11 --competitors:

- Each competitor sub-run now runs Step 0.55 (X handle / subreddits /
  GitHub) via resolve.auto_resolve inside the fanout closure. Deep-copied
  config per entity prevents _auto_resolve_context leak across sub-runs.
  Resolved data stored on report.artifacts["resolved"] for the renderer.
- New internal_subrun keyword on planner.plan_query and pipeline.run
  suppresses the LAW 7 "No --plan passed" stderr for engine-internal
  fan-out only. Default path unchanged.
- Default --competitors count is now 2 (3-way total). --competitors=N
  still customizes; range 1..6.
- SKILL.md STEP 0 canonical-path self-check forces readers who loaded
  from marketplaces/ (auto-restored to origin/main, stale) to re-read
  from plugins/cache/last30days-skill/last30days/{VERSION}/SKILL.md.
  Two of three 2026-04-22 test windows hit this stale-path trap.
- New ## Resolved Entities block in render_comparison_multi shows
  per-entity handles/subs/github for debug visibility.

Bumps plugin.json to 3.0.12. 12 new tests; 1,175 total passing.

Co-authored-by: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -116,7 +116,7 @@ When the same story appears on Reddit, X, and YouTube, v3 merges them into one c
 
 ### Auto-discovered competitor comparisons
 
-`/last30days OpenAI --competitors` discovers the top 3 peers via web search (Anthropic, xAI, Google Gemini), runs the full pipeline on each in parallel, and returns one N-way comparison report. Override with `--competitors=N` or `--competitors-list="A,B,C"`.
+`/last30days OpenAI --competitors` discovers the top 2 peers via web search (Anthropic, xAI), runs the full pipeline on each in parallel, and returns one 3-way comparison report. Override with `--competitors=N` (range 1..6) or `--competitors-list="A,B,C"`.
 
 ### GitHub person-mode