Remove [[wiki-links]], backlinks and the graph

Operator, 2026-08-22 (note 2897): ThoughtSync is an intermediary surface. You
write here because it's easy — a notebook in your pocket — and later you recall
the thing and go finish it somewhere else. Recall is the product; organization
is secondary. A linking system is organization, and it isn't what this is for.

So: `[[wiki-links]]`, backlinks, the `[[` autocomplete, the note_links table,
`/api/notes/link-search`, `/api/notes/<id>/backlinks`, the whole graph blueprint
and GraphView. Rust core loses `extract_links`, `backlinks`, `link_search` and
`create_titled`; the desktop loses the three Tauri commands that exposed them.

This subsumes 982d24c rather than reverting it. That commit bound links to a
note id so a rename would stop rewriting other notes' bodies — real infra, but
infra for a feature that is now gone, and nothing it added survives. Alembic
0023 stays in the chain anyway: it shipped in an image and may already be
applied, and deleting an applied revision strands a database's version pointer.
0024 drops the table and takes the column with it. The history stays honest
about the fact that it existed for a day.

Two things deliberately kept, because they were serving recall and only
incidentally serving links:

- `/api/notes/titles` and the titles store. The command palette lists them so
  you can jump to a note by name. `resolve()` — the name→note lookup that only
  linking needed — is gone.
- `display_title`. Every note still has a name for search results and export
  filenames. What that name is FOR changed; that it exists did not.

`notes/links.py` is now `notes/tags.py`, holding the #tag→label reconciliation
it always also owned. A file called links.py with no links in it would have been
exactly the drift this removal is meant to end.

Also swept out on the way: `_escape_like`, whose only caller was link-search,
and the `graph` icon. Nothing lost that a person typed — note_links was always
derived, and the `[[text]]` is still sitting in every body it was written in.

src/thoughtsync/models/all.py

@@ -10,7 +10,6 @@ from . import (  # noqa: F401
     note,
     note_attachment,
     note_item,
-    note_link,
     note_link_preview,
     note_revision,
     saved_filter,

src/thoughtsync/models/note.py

@@ -40,9 +40,9 @@ class Note(Base):
     )
     title: Mapped[str | None] = mapped_column(Text(), nullable=True)
     # The note's display NAME: explicit title if set, else the first non-empty body
-    # line (see notes.derive_display_title). Persisted + normalized-matched so every
-    # note — even a body-only one — is nameable, searchable, graphable, and
-    # [[wiki-link]]-able without forcing the user to type a title.
+    # line (see notes.derive_display_title). Persisted so every note — even a body-only
+    # one — has something to be called in search results and in an export filename,
+    # without forcing the user to type a title.
     display_title: Mapped[str] = mapped_column(Text(), nullable=False, server_default="")
     body: Mapped[str] = mapped_column(Text(), nullable=False, server_default="")
     color: Mapped[str] = mapped_column(Text(), nullable=False, server_default="default")

src/thoughtsync/models/note_link.py

@@ -1,47 +0,0 @@
-from __future__ import annotations
-
-import uuid
-
-from sqlalchemy import ForeignKey, Index, Text
-from sqlalchemy.dialects.postgresql import UUID
-from sqlalchemy.orm import Mapped, mapped_column
-
-from . import Base
-
-
-class NoteLink(Base):
-    """A [[wiki-link]] from a source note to another note.
-
-    Two target columns, and the pair is the point:
-
-    - ``target_id`` — the note this link actually points at, bound when the link was
-      written. This is what makes a link survive its target being RENAMED. A note's
-      name is derived from its first body line, so without an id the name is the
-      edge, and editing that line would silently break every inbound link (or, in the
-      older design, force a rewrite of every linking note's body).
-    - ``target_norm`` — the normalized link text, always stored. It is what an
-      UNRESOLVED link carries: `[[a note that doesn't exist yet]]` is a supported way
-      to create one, so a link has to be able to name a target that isn't there.
-
-    Resolution reads the id first and falls back to matching the norm against
-    ``notes.display_title``, which is how a forward link connects the moment its
-    target appears. ``_claim_unresolved_links`` then binds the id, so the fallback is
-    a transitional state rather than a permanent one.
-    """
-
-    __tablename__ = "note_links"
-    __table_args__ = (
-        Index("ix_note_links_target", "target_norm"),
-        Index("ix_note_links_target_id", "target_id"),
-    )
-
-    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
-    source_id: Mapped[uuid.UUID] = mapped_column(
-        UUID(as_uuid=True), ForeignKey("notes.id", ondelete="CASCADE"), nullable=False
-    )
-    # SET NULL rather than CASCADE: deleting the target un-resolves the link, it does
-    # not delete it. The link text is still sitting in the source's body.
-    target_id: Mapped[uuid.UUID | None] = mapped_column(
-        UUID(as_uuid=True), ForeignKey("notes.id", ondelete="SET NULL"), nullable=True
-    )
-    target_norm: Mapped[str] = mapped_column(Text(), nullable=False)