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>

skills/issue/scripts/issue.py

@@ -25,7 +25,6 @@ domain has. The file name is the id:
     assignees: [naudachu]
     milestone: v0.2
     depends: [migrate-schema]
-    wiki: [Simple Chains/Ideas/Chain core]
     origin: gitea
     gitea: owner/repo#42
     synced: 2026-08-07T18:40:00Z
@@ -115,8 +114,8 @@ ISSUE_ROOT = store_root()
 # Domain-owned metadata, in render order. Foreign keys render after these,
 # sorted, so the sync layer can add fields without touching this list.
 DOMAIN_KEYS = ["id", "state", "labels", "assignees", "milestone", "depends",
-               "wiki", "origin"]
-LIST_KEYS = {"labels", "assignees", "depends", "wiki"}
+               "origin"]
+LIST_KEYS = {"labels", "assignees", "depends"}
 STATES = ("open", "closed")
 
 # `origin` is "does this issue exist anywhere but here" — a fact about the
@@ -249,7 +248,7 @@ class Issue(object):
     """One unit of work. `extra` holds metadata this layer does not own."""
 
     def __init__(self, id="", title="", body="", state="open", labels=None,
-                 assignees=None, milestone="", depends=None, wiki=None,
+                 assignees=None, milestone="", depends=None,
                  origin=LOCAL, extra=None):
         self.id = id
         self.title = title
@@ -259,10 +258,6 @@ class Issue(object):
         self.assignees = list(assignees or [])
         self.milestone = milestone or ""
         self.depends = list(depends or [])
-        # Page TITLES this work is written up in — names for documents, which
-        # is why they are domain-owned. What a title resolves to is /tea:page's
-        # business, and this layer never asks: no path, no URL, no lookup.
-        self.wiki = list(wiki or [])
         self.origin = origin or LOCAL
         self.extra = dict(extra or {})
 
@@ -308,7 +303,7 @@ class Issue(object):
                    state=meta.get("state") or "open",
                    labels=lst("labels"), assignees=lst("assignees"),
                    milestone="" if ms == "none" else ms,
-                   depends=lst("depends"), wiki=lst("wiki"),
+                   depends=lst("depends"),
                    origin=meta.get("origin") or LOCAL, extra=extra)
 
     def to_text(self):
@@ -320,7 +315,6 @@ class Issue(object):
             "assignees": self.assignees,
             "milestone": self.milestone or "none",
             "depends": self.depends,
-            "wiki": self.wiki,
             "origin": self.origin,
         })
         body = self.body.strip() or "(no body)"