feat(annotations): bulk Add tags and Auto-tag selected as Activity jobs (#283)

* feat(activity): image tagging jobs for bulk Add tags and Auto-tag

POST /prompt_manager/jobs/image-tags starts one record-changing
"image-tags" job over 1..500 listed images (202, or the same 409 busy
envelope as /jobs/scan). Add tags hashes each current file and unions a
fixed set into that byte record; Auto-tag captures each still image, asks
one legacy engine for its top N suggestions on the capture (count from
the options or autotag.defaults.suggestion_limit), re-hashes the file and
unions only onto the same bytes. Outcomes are grouped as tagged,
unchanged, skipped (video, too large, file changed, file not found, not a
still image) and errors; cancel stops at a file boundary.

Auto-tag holds the shared model gate for the whole job (409 model-busy at
start when it is held), loads the model once and never downloads one: an
unavailable model fails the job before the first file. The registry gains
blocker() so a start answers busy before taking the gate.

* feat(annotations): Add tags and Auto-tag selected in the selection bar

The Images selection bar gains the concept's Add tags and, beside it,
Auto-tag selected (D85). Add tags starts the image-tags Activity job with
the dialog's comma-separated names; Auto-tag selected reuses the Tag image
model panel (server defaults, Suggestions count) without Generate, refuses
a model that is not downloaded, and either starts the job (Apply
automatically) or walks the selection one Tag image dialog at a time
(Review each image, D90). Busy, model-busy and refused starts toast why;
the selection stays; a finished job's files are read again.

* feat(activity): show image tagging jobs with their own outcomes

Image tagging jobs get their own Activity view (D89): the pill reads
"Tagging", the item and heading line name the images and end with
"N tagged · M errors", and the job view shows Tagged, Unchanged, Skipped
and Errors tiles and outcomes, opens Tagged and Unchanged rows in the
viewer, and reads "Tagging log" and "Cancel tagging". The per-kind table
lives in activity-store.mjs; the scan's view is unchanged.

The selection bar's copy without a concept line is recorded as D117.

* fix(annotations): final review round for bulk image tagging

- Rename the D117 copy deviation to D118 (D117 belongs to another PR).
- The tagging job's progress line gives the scan's "about X min left"
  estimate, with each finished file as one batch.
- The start body cap fits 500 targets of the longest legal path, even
  escaped; one byte over answers 413.
- A capture store at capacity is retried with a short backoff, then the
  file is skipped with a rerun sentence instead of a Tag-dialog error.
- Output roots and their labels are resolved once per job in the
  executor, not twice per file on the event loop.
- Review each image holds Stop reviewing, Escape and x while a save is in
  flight, and its primary reads "Save and next" when only the manual
  field would be saved.
- An Add tags field that parses to no names keeps the dialog and its
  text and reports the message on the field.
- Image tagging finish toasts carry the counts ("... finished · N tagged
  · M errors").
- Specs: the bulk spec waits for the answered Start before checking that
  the invalid press sent nothing; the Activity spec uses a real error row.

py/api/__init__.py

@@ -7,6 +7,7 @@ Split into domain-specific mixins for maintainability:
 - LoggingRoutesMixin: log management endpoints
 - AutotagRoutesMixin: auto-tagging model management and tagging
 - JobRoutesMixin: the session job registry behind Activity (py/api/jobs.py)
+- ImageTagJobsMixin: bulk Add tags / Auto-tag as image-tags jobs
 """
 
 import asyncio
@@ -32,6 +33,7 @@ from .history import HistoryRoutesMixin
 from .images import ImageRoutesMixin
 from .admin import AdminRoutesMixin
 from .job_routes import JobRoutesMixin
+from .image_tag_jobs import ImageTagJobsMixin
 from .jobs import JobRegistry
 from .logging_routes import LoggingRoutesMixin
 from .autotag_routes import AutotagRoutesMixin
@@ -260,6 +262,7 @@ class PromptManagerAPI(
     ImageRoutesMixin,
     AdminRoutesMixin,
     JobRoutesMixin,
+    ImageTagJobsMixin,
     LoggingRoutesMixin,
     AutotagRoutesMixin,
     LoraIntegrationMixin,