feat(types)!: drop the blob column type (ADR-0005 Amendment 2)

blob was a dead-end: declarable but never fillable (no literal in either
mode, seed-unsupported), so a blob column could only ever hold NULL. Remove
Type::Blob + Value/CellValue::Blob + the base64 CSV path + the grammar slot
+ completion/render/type-change/seed handling + the binder refusal (whose
message also carried a user-facing "DSL" copy-rule bug). The vocabulary is
now nine types; base64 stays (clipboard OSC-52).

Backward compat is the ADR-0015 migration framework's first real use: a
v1->v2 format bump (CURRENT_SCHEMA_VERSION across serializer/parser/skeleton)
with a migrator that rewrites `type: blob` -> `type: text`, and a forced .db
rebuild from the migrated text when a blob column was actually converted
(the stale .db keeps a STRICT BLOB engine column). Conversion to text is
non-destructive and CSV-free. Covered by a full-stack integration test and a
Tier-4 PTY test that opens a real legacy v1-blob project.

Also sweeps the nine-type vocabulary through CLAUDE.md, requirements.md, the
website (type reference, seed doc, highlight grammar), and the ADR-0030/0033/
0035 cross-references; CHANGELOG Removed entry; handoff-79.

BREAKING CHANGE: the `blob` column type is removed. Existing projects that
declared a blob column are migrated on first open (the column becomes text;
the original project.yaml is kept as a .v1.bak).

tests/it/seed.rs

@@ -617,69 +617,6 @@ fn seed_refuses_when_a_parent_table_is_empty() {
     );
 }
 
-#[test]
-fn seed_refuses_a_not_null_blob_column() {
-    let (_project, db, _dir) = open_project_db();
-    let rt = rt();
-    let mut payload = ColumnSpec::new("payload", Type::Blob);
-    payload.not_null = true;
-    rt.block_on(db.create_table(
-        "Files".to_string(),
-        vec![ColumnSpec::new("id", Type::Serial), payload],
-        vec!["id".to_string()],
-        None,
-    ))
-    .expect("create Files");
-
-    let err = rt
-        .block_on(db.seed(
-            "Files".into(),
-            None,
-            Some(2),
-            Vec::new(),
-            Some(1),
-            Some("seed Files 2".into()),
-        ))
-        .expect_err("seed must refuse a NOT NULL blob");
-    let msg = err.to_string();
-    assert!(
-        msg.contains("payload") && msg.to_lowercase().contains("blob"),
-        "error should name the un-generatable blob column: {msg}"
-    );
-}
-
-#[test]
-fn seed_omits_a_nullable_blob_column() {
-    let (project, db, _dir) = open_project_db();
-    let rt = rt();
-    rt.block_on(db.create_table(
-        "Files".to_string(),
-        vec![
-            ColumnSpec::new("id", Type::Serial),
-            ColumnSpec::new("name", Type::Text),
-            // nullable blob → omitted (→ NULL), seed still succeeds.
-            ColumnSpec::new("payload", Type::Blob),
-        ],
-        vec!["id".to_string()],
-        None,
-    ))
-    .expect("create Files");
-
-    let res = rt
-        .block_on(db.seed(
-            "Files".into(),
-            None,
-            Some(3),
-            Vec::new(),
-            Some(1),
-            Some("seed Files 3".into()),
-        ))
-        .expect("seed succeeds despite the nullable blob");
-    assert_eq!(res.produced, 3);
-    let csv = read_csv(&project, "Files").expect("Files CSV");
-    assert_eq!(data_row_count(&csv), 3);
-}
-
 // — uniqueness, junction distinct-combos, IN-CHECK (D10 / D14 / D17) —
 
 /// The `n`th comma-separated field of each data row (the generated