Docs: consolidate active planning and archive historical material

The planning package had grown to where a new agent could not tell what was
authoritative. Phase 0 execution prompts sat beside the specification; four
completed milestone reports sat beside the current one; and upstream AI-DnD's
own `plan/` build log and `docs/` project site still described a hosted,
scripted, multi-user product with accounts — every screenshot in it showed a
Scripts tab and a Sign up button, none of which has existed since M2.

`planning/archive/` now holds the history and says so in its own README:
`phase0/` for the research that chose AI-DnD, `milestone-reports/` for M1 and
M2, `decisions/` for ADR 008, the Phase-0-before-build gate Phase 0 satisfied.
`planning/reports/` holds only the current milestone's report, because that is
the one M4 planning has to read; it moves to the archive when M4's replaces it.

Deleted rather than archived: the Phase 0B execution prompts and the
handoff/status/summary documents, the Phase 0A discovery and triage reports,
upstream's `plan/` and `docs/` trees, and `frontend/README.md`, which was Vite's
template boilerplate. All of it is in Git history, and the two recommendation
reports carry every conclusion the deleted research reached.

Archived documents are kept verbatim. Paths written inside them point at where
those files were when the document was written, which is the point: an evidence
record that has been quietly edited is no longer evidence.

Active documentation is corrected where it pointed at the removed trees or
described removed capability as present. `DEVELOPMENT.md`'s "things M1 did not
touch" list had gone stale at M2 and claimed QuickJS scripting was still tested;
its test count was 604 against an actual 638. `README.md` loses the upstream CI
badge, which reported upstream's pipeline rather than this fork's, and a
reference to `backend/app/worldstate/engine.py`, a file that does not exist.
`planning/README.md` is rewritten as the documentation index.

New: `planning/PROJECT-SOURCES.md` and `planning/project-sources.txt`, the
manifest of what belongs in the ChatGPT project's Sources.

Source comments referring to the deleted trees are reworded; no behaviour
changes. 638 backend tests pass, frontend lints and builds, and a reference scan
over all 48 tracked Markdown files reports no unresolved path in active
documentation.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NCbwH7yLGKsj1rhXXzKSCu

planning/archive/phase0/PHASE-0B-OFFLINE-NETWORK.md

@@ -0,0 +1,106 @@
+# Phase 0B — Offline and Network Behavior
+
+Method: a Docker network created with `--internal` (no NAT, no DNS to the
+outside). The Ollama container was attached to it so the app could reach a model
+while having no path to the Internet. Isolation was verified from inside the
+app container before testing:
+
+```
+blocked ('1.1.1.1', 443)              OSError
+blocked ('openrouter.ai', 443)        gaierror
+blocked ('fonts.googleapis.com', 443) gaierror
+```
+
+## AI-DnD — fails offline as shipped; fine once one file is vendored
+
+First turn on the isolated network died. The SSE stream emitted the `player`
+event and stopped. Container log:
+
+```
+requests.exceptions.ConnectionError: HTTPSConnectionPool(
+  host='openaipublic.blob.core.windows.net', port=443):
+  Max retries exceeded with url: /encodings/cl100k_base.tiktoken
+  (NameResolutionError ... Temporary failure in name resolution)
+```
+
+`tiktoken` downloads its BPE encoding on first use, and AI-DnD calls it for
+context budgeting on every turn. On the host this was invisible, because the
+file had already been cached to `/tmp/data-gym-cache/9b5ad71b…` during an
+earlier online run.
+
+After copying that 1.7 MB file into the container:
+
+```
+OFFLINE TURN GENERATED: "I am Vale, an explorer. I journey alone through the
+darkened depths of the lighthouse..."
+```
+
+So: a hard blocker on a clean air-gapped install, and a packaging fix — vendor
+the encoding (or pre-seed `TIKTOKEN_CACHE_DIR`, or replace the tokenizer). Worth
+stressing that **static analysis could not have found this**; it took an actually
+isolated run.
+
+Other AI-DnD network surface:
+
+- **Google Fonts at runtime.** The built SPA's `index.html` still contains
+  `fonts.googleapis.com/css2?family=Cinzel...&family=Crimson+Pro...&family=Inter...`,
+  and `main.py`'s CSP explicitly allows `fonts.googleapis.com` /
+  `fonts.gstatic.com`. Violates specification §12. Fix: self-host three families.
+- Only other remote host in backend Python is `https://openrouter.ai/api/v1`,
+  used as a default endpoint constant and a header-attribution host check. Both
+  removable with the cloud-provider path.
+- `analytics.py` is a **self-hosted** counter writing to two local tables. No
+  third-party script, no outbound request. It records no IP, no user agent, and
+  hashes the user id with HMAC. Removable, and not a telemetry leak in the
+  meantime.
+- Connection test and turns honour the configured endpoint only; no automatic URL
+  retrieval or content fetching was observed.
+
+## Open Dungeon — runtime clean, build and telemetry are not
+
+- **Next.js telemetry is on by default** and printed its notice on first start.
+  Needs `NEXT_TELEMETRY_DISABLED=1` or `next telemetry disable` in the
+  production configuration.
+- **Fonts are fine at runtime.** `layout.tsx` uses `next/font/google`, which
+  downloads at *build* time and self-hosts. The served page contains no
+  `fonts.googleapis.com` reference. The trade-off is that the build needs
+  network access.
+- Remote hosts referenced in `src/`: `openrouter.ai` (preset provider URL and a
+  model list), plus `ko-fi.com` and `github.com/sponsors` donation links in the
+  UI. Everything else is `127.0.0.1` / `localhost` (13 occurrences).
+- Local story play needs no cloud service: Ollama for text, a local FLUX worker
+  or the user's own ComfyUI for images.
+- 335 npm packages with 6 high-severity advisories is the largest supply-chain
+  surface of the three.
+
+## ai-adventure — verifiably local-only
+
+The strongest posture by a wide margin, and the easiest to audit:
+
+- **Exactly one outbound call site in the whole codebase**: `urlopen` in
+  `llm/lm_studio.py`. Nothing else in `local_adventure/` opens a socket.
+- **No hardcoded remote host anywhere.** The only `http` string in the package is
+  the scheme check in `content/models.py`.
+- **One direct dependency** (`pydantic`), six packages in the closure.
+- It is the only candidate that already implements specification §12's
+  non-local-endpoint warning:
+
+```python
+def _endpoint_warnings(config):
+    hostname = urlparse(config.model.base_url).hostname
+    if hostname not in {"127.0.0.1", "localhost", "::1"}:
+        return ["model.base_url is not loopback; game prompts and content will
+                 be sent to that endpoint. Enable API authentication."]
+```
+
+- `audit.store_prompts` defaults to `false`, with prompt *hashes* stored instead.
+- Tests, world validation, session creation, replay, branching and export are all
+  offline by construction.
+
+## Summary
+
+| | Local play works offline | Cloud service required | Telemetry / remote assets | Removal difficulty |
+|---|---|---|---|---|
+| AI-DnD | **Only after vendoring the tiktoken encoding** | No | Google Fonts at runtime; local-only analytics tables | Low — one vendored file, three self-hosted fonts, delete analytics |
+| Open Dungeon | Yes at runtime; build needs network | No | Next.js telemetry on by default | Low — one env var; fonts already self-hosted |
+| ai-adventure | **Yes, unconditionally** | No | **None** | Nothing to remove |