revert: remove the placement reconciler — it manufactured the problem it solved

Milestone #421 built a sweep that compared each image's `artist_id` to the
name of the directory holding its file, and called every mismatch a misplaced
image. It reported 33,789 of 63,605 as wrongly filed. That number described
the comparison, not the library.

What it actually was:

  32,475  (97.1%)  one artist's own folder, spelled differently
                   — Telepurte/ vs telepurte/. Same artist, same art.
     657  ( 2.0%)  loose at the images root
     328  ( 1.0%)  in a folder named after a different artist

And the 1% did not mean what the tool assumed either. `ImageProvenance`
records the post and source every file was downloaded from — the
authoritative answer, which the tool never consulted. Querying it for all 328:

    144  provenance agrees with the record  (move would be right)
     87  provenance agrees with the FOLDER  (the record is wrong; move wrong)
     53  provenance names SEVERAL artists   (no single correct folder)
     41  no provenance at all
      3  agrees with neither

So the sweep would have misfiled or arbitrarily picked for ~41% of the only
set it was really needed for. The system already knew where each file came
from; the tool inferred it from a column and a directory name instead.

Operator, 2026-09-21: *"the current system consistently records where items
are and where they came from this is just complicating something works and
doesn't need fixing."* Correct on both counts.

Removed: the service, the tasks, the model and migration 0099's table, the
/api/cleanup/layout and /placement/* endpoints, the Maintenance card and its
store actions, and the tests. 0100 drops the table (rule #22 — no legacy).

KEPT deliberately, per the operator:
- `utils.paths.canonical_subdir` — new filesystem imports derive their
  directory from the artist's slug, matching what the downloader always did.
  Not part of this tool; removing it would be churn that fixes nothing.
- The 327 files run 1 moved (InsoUwu/ -> insouwu/). Same artist either way,
  and the gallery renders them correctly.
- Everything from #4223 (three-gate dedup, 256-bit pHash) and #4234 (backup
  credential exclusion). Those fixed problems that were actually reported.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LVjrnpQjRgHdvq95rASoiR

alembic/versions/0100_drop_library_placement_run.py

@@ -0,0 +1,109 @@
+"""Drop library_placement_run — the placement reconciler is removed.
+
+Milestone #421 built a sweep that compared each image's `artist_id` to the
+name of the directory its file sat in, and called every mismatch a misplaced
+file. On the operator's library that reported 33,789 of 63,605 images as
+wrongly filed.
+
+That number was an artefact of the comparison, not a fact about the library:
+
+- **97.1%** of it was one artist's own folder spelled differently —
+  `Telepurte/` versus `telepurte/`. Same artist, same art, nothing wrong.
+- Of the 1% that sat in a differently-named folder, querying `ImageProvenance`
+  — which records the post and source each file was actually downloaded from —
+  showed 87 where provenance agreed with the FOLDER and not the record, and 40
+  genuinely posted by several creators. The sweep would have misfiled or
+  arbitrarily picked for roughly 41% of that set.
+
+The system already knows where every file came from. The reconciler inferred
+it from a column and a directory name instead, and manufactured work out of a
+naming convention. Operator's call, 2026-09-21: *"the current system
+consistently records where items are and where they came from this is just
+complicating something works and doesn't need fixing."*
+
+Rule #22 — no legacy to preserve. The table goes with the code.
+
+## What is deliberately kept
+
+`utils.paths.canonical_subdir` stays: new filesystem imports derive their
+directory from the artist's slug, matching what the downloader has always
+done. It is not part of this tool and removing it would be churn for no fix.
+Run 1's 327 moved files (`InsoUwu/` -> `insouwu/`) also stay where they are —
+same artist either way, and the gallery renders them correctly.
+
+Revision ID: 0100
+Revises: 0099
+Create Date: 2026-09-21
+
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+from sqlalchemy.dialects import postgresql
+
+revision: str = "0100"
+down_revision: Union[str, None] = "0099"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.drop_index(
+        "ix_library_placement_run_artist_id",
+        table_name="library_placement_run",
+    )
+    op.drop_index(
+        "ix_library_placement_run_status", table_name="library_placement_run",
+    )
+    op.drop_table("library_placement_run")
+
+
+def downgrade() -> None:
+    # Recreates the table only. The three runs it held (one applied, two
+    # planned-and-never-run) are not restored and are not worth restoring —
+    # the code that reads them is gone.
+    op.create_table(
+        "library_placement_run",
+        sa.Column("id", sa.Integer(), nullable=False),
+        sa.Column(
+            "status", sa.String(length=16), server_default="running",
+            nullable=False,
+        ),
+        sa.Column("artist_id", sa.Integer(), nullable=True),
+        sa.Column(
+            "started_at", sa.DateTime(timezone=True),
+            server_default=sa.text("now()"), nullable=False,
+        ),
+        sa.Column("finished_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column(
+            "planned_count", sa.Integer(), server_default="0", nullable=False,
+        ),
+        sa.Column(
+            "moved_count", sa.Integer(), server_default="0", nullable=False,
+        ),
+        sa.Column(
+            "refused_count", sa.Integer(), server_default="0", nullable=False,
+        ),
+        sa.Column(
+            "moves", postgresql.JSONB(astext_type=sa.Text()),
+            server_default=sa.text("'[]'::jsonb"), nullable=False,
+        ),
+        sa.Column(
+            "refusals", postgresql.JSONB(astext_type=sa.Text()),
+            server_default=sa.text("'[]'::jsonb"), nullable=False,
+        ),
+        sa.Column("error", sa.Text(), nullable=True),
+        sa.ForeignKeyConstraint(
+            ["artist_id"], ["artist.id"],
+            name="fk_library_placement_run_artist_id", ondelete="SET NULL",
+        ),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_index(
+        "ix_library_placement_run_status", "library_placement_run", ["status"],
+    )
+    op.create_index(
+        "ix_library_placement_run_artist_id", "library_placement_run",
+        ["artist_id"],
+    )