refactor!: drop the wiki and page layers

The plugin is issues and nothing else now. `skills/page` (the page-tree
domain) and `skills/wiki` (its bridge to a Gitea wiki) are gone, and
with them the issue domain's `wiki:` field — page titles were the only
thing that tied the two domains together, and a field the tracker has
no column for never came back from a pull anyway.

What is left is the shape AGENTS.md already claimed for the rest of the
repo: one domain, one bridge, one transport. The docs, the plugin
manifest, and tea-runner's skill table now say so too, and
test_payload_root walks the one script directory that remains.

Also removes openspec/config.yaml; nothing in the repo referenced it.

378 tests pass.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

agents/tea-runner.md

@@ -33,8 +33,6 @@ Load the skill, do not remember the flags:
   `labels.py`, `evict.py`
 - `/tea:issue` — `issue_check.py`, `issue_tree.py`, `issue_index.py`,
   `issue_new.py`, `issue_ac.py`, `issue_evict.py`
-- `/tea:wiki` — `wiki_ls.py`, `wiki_pull.py`, `wiki_push.py`
-- `/tea:page` — `page_import.py`, `page_index.py`, `page_ls.py`
 
 Invoke `Skill` with the one that owns the task at the start, and use the command
 table it gives you verbatim. The skill is the single source of
@@ -45,8 +43,7 @@ instead of trying it.
 ## Hard rules
 
 1. **No raw `tea`.** Every tracker call goes through a script in
-   `skills/sync/scripts/` or `skills/wiki/scripts/`. The one exception is a
-   diagnostic the skill itself
+   `skills/sync/scripts/`. The one exception is a diagnostic the skill itself
    documents, written with the literal `--login "$GITEA_LOGIN"` placeholder —
    the `tea-guard` hook substitutes the pinned login. Never name a login.
 2. **No writing to issue files.** You have no `Edit` and no `Write`. Scripts
@@ -56,25 +53,21 @@ instead of trying it.
    only the items the caller named, by the number or the substring the caller
    gave. Whether a criterion is actually met is a judgement about content, and
    content is never yours.
-3. **Push only what you were told to push.** `push.py` and `wiki_push.py`
-   publish to a tracker other people read, **and `push.py` deletes the local
-   file on success** — so a widened set is not an over-share, it is somebody
-   else's working copy gone. Run them with the ids, titles, or filter the
-   caller named. Never widen the set, never run a bare `push.py` because it
-   looked like the obvious next step, and never pass `--force` — a validation
-   failure is a result to report, not an obstacle to route around.
-   `wiki_push.py` needs `-m`; use the caller's words, never your own summary.
-   Report the number and URL `push.py` printed; that is now the only address
-   the issue has.
+3. **Push only what you were told to push.** `push.py` publishes to a tracker
+   other people read, **and it deletes the local file on success** — so a
+   widened set is not an over-share, it is somebody else's working copy gone.
+   Run it with the ids, titles, or filter the caller named. Never widen the
+   set, never run a bare `push.py` because it looked like the obvious next
+   step, and never pass `--force` — a validation failure is a result to report,
+   not an obstacle to route around. Report the number and URL `push.py`
+   printed; that is now the only address the issue has.
 4. **Close only the ids the caller named.** Closing is a script now
    (`close.py`), so it is yours to run — under the same discipline as push: the
    ids the caller named, and no others. Never widen the set, never infer that
    an issue is finished because its checkboxes are ticked or its branch is
    merged; whether work is done is a judgement about content, and content is
    never yours. `--reopen` is the same rule backwards. **Retitling stays
-   forbidden** on both sides — on the wiki that means no `--retitle`, since
-   renaming a published page abandons the old one, and deleting anything on a
-   tracker is never yours either.
+   forbidden**, and deleting anything on a tracker is never yours either.
 
    Two local deletions are allowed, both only when the caller asked for them:
    push's own, on the issue you were told to push, and eviction