core, web: pin, archive and reorder a note someone shared with you

Schema v12 adds notes.state_at: a recipient's own pin, archive and order are
stamped there instead of on updated_at, which stays the text's time. Push sends
them only to a server advertising `shared_state` (push::Accepts), a view share
included; the first pull at that level starts the feed over once so held copies
drop their owner's pins. The client speaks protocol 7 and lists `shares` and
`shared_state` among the features a server may lack.

The web card and editor offer pin, archive and drag on shared notes; share and
trash stay the owner's, and the board's trash key skips notes you don't own.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

core/src/local/schema.rs

@@ -311,6 +311,20 @@ ALTER TABLE notes ADD COLUMN shared_by_name TEXT;
 ALTER TABLE sync_state ADD COLUMN shares_synced INTEGER NOT NULL DEFAULT 0;
 "#;
 
+// v12 (#5176): a shared note's pin, archive and position are this account's own.
+//
+// `state_at` is when they last changed here, on a note someone else owns. It is kept
+// apart from `updated_at`, which stays the time of the note's TEXT: pinning a copy
+// whose text is behind the owner's must not make that text look like the newer
+// edit when it is pushed. Null on our own notes, where `updated_at` covers both.
+//
+// `sync_state.shares_synced` now holds a level rather than a flag (see
+// `state::SHARED_STATE`), and a device reaching this level pulls everything once
+// more: the shared notes it holds carry their owner's pins until it does.
+const SCHEMA_V12: &str = r#"
+ALTER TABLE notes ADD COLUMN state_at TEXT;
+"#;
+
 pub fn migrate(conn: &Connection) -> rusqlite::Result<()> {
     conn.execute_batch("PRAGMA foreign_keys = ON;")?;
     let version: i64 = conn.query_row("PRAGMA user_version", [], |r| r.get(0))?;
@@ -358,6 +372,10 @@ pub fn migrate(conn: &Connection) -> rusqlite::Result<()> {
         conn.execute_batch(SCHEMA_V11)?;
         conn.execute_batch("PRAGMA user_version = 11;")?;
     }
+    if version < 12 {
+        conn.execute_batch(SCHEMA_V12)?;
+        conn.execute_batch("PRAGMA user_version = 12;")?;
+    }
     Ok(())
 }
 
@@ -472,7 +490,7 @@ mod tests {
         let version: i64 = conn
             .query_row("PRAGMA user_version", [], |r| r.get(0))
             .expect("version");
-        assert_eq!(version, 11);
+        assert_eq!(version, 12);
     }
 
     /// Every attachment that predates v10 came down the feed, so it is already on the