feat: evict closed issues from the local store

The store is a working set, not an archive. Until now nothing removed a
closed issue from it: #10 put a filter on the write and said so explicitly
("existing store files are not cleaned"), and the migration was never
anybody's job. The only way out was rm past every script, followed by
rebuilding INDEX.md by hand.

issue_evict.py removes <id>.md and every sidecar under that slug for an
issue that is state: closed AND carries an origin: naming a tracker, then
rebuilds INDEX.md. --dry-run prints and writes nothing at all.

Two conditions, and the second one is the whole safety argument. An
origin: local issue IS the work — there is no other copy — so it is never
evicted, in any state, not even when named on the command line: it is
reported and kept. The only files that go are ones whose own metadata says
pull.py <n> brings them back, which is the trade push.py already makes
when it drops a file the tracker just confirmed.

The command lives in the domain layer, and the layering rule decides that
rather than convenience: state: and origin: are domain fields and the
answer is already on disk, so eviction needs no network, no login and no
tea. The domain also gains issue.slug_files — every file the store holds
under one slug, which is all_ids' "a slug has no dot in it" read the other
way round, and lets the domain remove an issue completely without learning
what a comment thread is.

skills/sync/scripts/evict.py is the bridge form, and it exists because a
local state: is only as fresh as the last pull: an issue closed in the web
UI still reads open here. It refreshes state: from Gitea, then calls
issue_evict.run — one implementation of "what may be evicted", in the
layer that owns the fields it reads. Same gate as push, one step earlier:
every candidate's state is fetched before anything is removed, each answer
must be an object carrying the number asked about and a state the domain
recognizes (confirmed_state, the counterpart of confirmed_number), and a
failed or unconfirmed call evicts nothing — not even the candidates whose
answers had already arrived, and no refreshed state: is written back
either. A candidate is an issue with a gitea: handle; origin: local has
none, is never asked about, and is never removed.

.remote.json is deliberately not pruned. It is the number -> slug ledger,
its entries are supposed to outlive the files they name, and an evicted
issue is in exactly the state a pushed one is.

AGENTS.md gains the rule the tracker side never wrote down: pull by number
fetches an issue in any state — an address is not a query. Eviction does
not revoke it, so a closed issue pulled after a cleanup is on disk again,
and that is the tracker answering what it was asked.

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

agents/tea-runner.md

@@ -29,9 +29,10 @@ to fill the gap yourself.
 
 Load the skill, do not remember the flags:
 
-- `/tea:sync` — `pull.py`, `push.py`, `comment.py`, `remote.py`, `labels.py`
+- `/tea:sync` — `pull.py`, `push.py`, `comment.py`, `remote.py`, `labels.py`,
+  `evict.py`
 - `/tea:issue` — `issue_check.py`, `issue_tree.py`, `issue_index.py`,
-  `issue_new.py`, `issue_ac.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`
 
@@ -67,8 +68,13 @@ instead of trying it.
    the issue has.
 4. **Do not close, delete, or retitle anything** on either side. On the wiki
    that means no `--retitle`: renaming a published page abandons the old one.
-   The one deletion you may cause is push's own, on the issue you were told to
-   push.
+   Two deletions are allowed, both local and both only when the caller asked for
+   them: push's own, on the issue you were told to push, and eviction
+   (`issue_evict.py` / `evict.py`) of closed issues. Run eviction with
+   `--dry-run` first and report what it named; never widen the set past what the
+   caller said. It refuses to touch an `origin: local` issue by itself — that is
+   the script's guarantee, not your judgement, and it is not a reason to point
+   it at a store nobody asked you to clean.
 5. **One retry, maximum.** A command that fails twice is a finding. Do not
    permute flags looking for one that works.
 6. **No payload dumps.** Never run `tea issues -o json`, never `cat` a pulled