fix(tagging): legacy pages tag each image, not its prompt (#379, PR 2) (#394)

* fix(tagging): Tag output images tags each image, not its prompt (#379, PR 1)

The native "Tag output images" job now runs the image-tags loop over every
still image the output folders list, linked or not: each image gets its own
model tags (at most "Suggestions per image") in its image tag set, and its
bytes are marked auto-tagged in a new media_image_autotags table. No prompt
tag or prompt text is written.

- database/autotag_schema.py: one forward-only WITHOUT ROWID table, optional
  in old backups, refused without the annotation group.
- add_image_tags/replace_image_tags take mark_autotagged; autotag_state and
  autotagged_locators read the marks through the one current-record rule.
- "Skip already tagged" skips images whose current bytes are marked, counted
  in a stat-only pre-pass; hand tags do not count.
- The review counts images and estimates the time (WD14 on CPU or CUDA).
- System > Auto-tagging review rows and copy, D134 and the Auto-tagging
  contract follow.

Part of #379

* fix(tagging): end the batch job after its cleanup and report pre-pass progress (#379)

The job read as ended while it still held the model gate, so a quick
restart could be refused with model-busy. Pre-pass chunks now publish
progress, and a cancel between chunks keeps exact counts.

Part of #379

* fix(tagging): measured GPU rate, and an ended image-tags job shows no time left (#379)

The live check measured WD14 on CUDA at 0.167 s per image (100 images in
16.7 s with the model load), so the review estimate uses 0.17 s. A finished
or cancelled Auto-tag/Add tags job kept "Processing file N of N · about X
min left"; it now ends with "<verb> <state> · N files processed".

Part of #379

* fix(tagging): legacy pages tag each image, not its prompt (#379, PR 2)

The admin and gallery batch starts the shared Tag output images job
("Tag output images (legacy page)") and relays its progress; closing the
window cancels it. Review asks per image with Skip first and applies by
image and sha256; apply refuses a prompt_id body. The Tag image dialog
marks an image auto-tagged only after Generate suggestions on that
capture. A second legacy batch (also one that wins the start race)
answers JSON 409, and both pages now show that sentence.

* test(tagging): gallery review units apply by image; record each progress change

The gallery review unit tests still pinned the removed prompt_id apply.
The legacy batch spec read the progress text once per observer callback,
so a phase frame and the first image frame landing in one task lost the
phase (WebKit); it now records every mutation record.

tests/test_database.py

@@ -1398,50 +1398,6 @@ class TestModelHousekeeping(DatabaseTestCase):
         self.assertIsNot(self.db.model.get_connection(), failing)
 
 
-class TestAutotagBatchCandidates(DatabaseTestCase):
-    """#328: the batch's candidate read never loads workflow documents."""
-
-    def test_autotag_candidates_skip_workflow_data(self):
-        from utils.hashing import generate_prompt_hash
-
-        first = self.db.save_prompt(
-            text="a", tags=["one", "two"], prompt_hash=generate_prompt_hash("a")
-        )
-        second = self.db.save_prompt(text="b", prompt_hash=generate_prompt_hash("b"))
-        old = self.db.link_image_to_prompt(
-            first, "/out/a.png", {"workflow": {"big": "x" * 1000}}
-        )
-        new = self.db.link_image_to_prompt(second, "/out/b.png")
-        statements = []
-        conn = self.db.model.get_connection()  # this thread's own connection
-        conn.set_trace_callback(statements.append)
-        try:
-            rows = self.db.autotag_batch_candidates()
-        finally:
-            conn.set_trace_callback(None)
-        self.assertEqual(
-            rows[0],
-            {
-                "id": new,
-                "image_path": "/out/b.png",
-                "prompt_id": second,
-                "prompt_tags": [],
-            },
-        )
-        self.assertEqual(
-            {**rows[1], "prompt_tags": sorted(rows[1]["prompt_tags"])},
-            {
-                "id": old,
-                "image_path": "/out/a.png",
-                "prompt_id": first,
-                "prompt_tags": ["one", "two"],
-            },
-        )
-        self.assertEqual(len(rows), 2)
-        self.assertTrue(statements)
-        self.assertFalse(any("workflow_data" in sql for sql in statements))
-
-
 if __name__ == "__main__":
     unittest.main()