chore: drop tracked output/ sample in favor of CI-built demo gallery (#4)

The dracula sample under output/dracula/ was a reference render for the
README. Now that demo/ auto-generates every card × every theme on each
push, the sample is redundant — and keeping it trackers means every
behavioral tweak shows up as a diff in committed SVGs.

- Delete output/dracula/*.svg.
- .gitignore: collapse `output/*` + `!output/dracula/` to a plain `output/`.
- demo.yml: drop `output/**` from paths-ignore (no longer part of any push).
- README / docs: point readers at demo/ instead of output/dracula/.

docs/codebase-summary.md

@@ -45,8 +45,8 @@ ghstats/
 │   └── demo.yml                         # Renders every theme for the repo owner on push to main
 ├── docs/                                # This directory
 ├── plans/                               # Research reports + implementation plans
-├── demo/                                # Auto-generated gallery — every card × every theme + README
-└── output/dracula/                      # Sample committed; other themes gitignored
+└── demo/                                # Auto-generated gallery — every card × every theme + README
+                                         # (`output/` is entirely gitignored; see demo/ for reference renders)
 ```
 
 ## Module responsibilities

docs/project-roadmap.md

@@ -78,7 +78,7 @@ Card count: 9 → 14. `FetchProductive` still pays for commit-history pagination
 
 - New `.github/workflows/demo.yml` renders every card for every theme against the repo owner's profile on each push to `main`.
 - Output lands in `demo/<theme>/`, with an auto-generated `demo/README.md` TOC so reviewers can browse palettes side-by-side with real data instead of cloning and running the CLI.
-- Loop prevention: workflow skips pushes that only touch `demo/**`, `output/**`, `**.md`, or `LICENSE`; `GITHUB_TOKEN`-driven pushes don't retrigger workflows by design.
+- Loop prevention: workflow skips pushes that only touch `demo/**`, `**.md`, or `LICENSE`; `GITHUB_TOKEN`-driven pushes don't retrigger workflows by design.
 - Consumer impact: none — this is a repo-internal discovery aid, not a shipped feature.
 
 ---