docs: mark P0–P4 done, add SMOKE recipe, refresh README

State drift after P0–P4 completion + 3 post-merge hotfixes (PR #20
--config across subcommands, PR #24 --config in kb ask, PR #25 RRF
fusion_score normalization). README still framed the project as
"spec frozen, code 0 lines"; phase docs and task specs all carried
status: planned. Sweep:

- README.md: top banner now "P0–P4 done (17/31 tasks) + 3 hotfixes
  applied"; command table marks each subcommand's owning phase and
  current status (kb ask = ✅ via P4-3, kb eval = ⏳ P5);
  phase roadmap table grew a Status column (P0–P4 completed, P5
  next, P6–P9 pending); component count bumped 30 → 31 to reflect
  P3-5 (app-wiring, post-spec); core decisions table notes the
  RRF [0,1] normalization invariant; build+실행 section drops the
  "P0 미시작" caveat; new pointers to HOTFIXES.md and SMOKE.md.
- docs/SMOKE.md (new): ~80-line recipe for running the full
  pipeline against an isolated /tmp/kb-smoke/ workspace via
  --config, without polluting ~/.config/kb/ or
  ~/.local/share/kb/. Covers fixture seeding, sample config.toml
  with the post-merge defaults, doctor → ingest → list →
  search × 3 modes → inspect → ask sequence, verification
  checklist, and known-behaviour notes (fastembed model
  download, RAG response time, --config hard-fail on missing
  path).
- tasks/phase-{0..4}-*.md: status frontmatter flipped planned →
  completed.
- tasks/p0/, tasks/p1/, tasks/p2/, tasks/p3/, tasks/p4/: same
  status flip across all 17 component task specs (1+6+2+5+3).
  P5–P9 stay planned.

cargo test --workspace: 319 passed; clippy clean (no source
changes in this commit, just docs + frontmatter).

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

tasks/p3/p3-5-app-wiring.md

@@ -3,7 +3,7 @@ phase: P3
 component: kb-app (facade wiring)
 task_id: p3-5
 title: "Wire kb-app facade — ingest / search / list / inspect end-to-end"
-status: planned
+status: completed
 depends_on: [p1-6, p2-2, p3-2, p3-3, p3-4]
 unblocks: [p4-3, p9-1, p9-2, p9-4]
 contract_source: ../../docs/superpowers/specs/2026-04-27-kb-final-form-design.md