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).

src/output_render.rs

@@ -345,7 +345,7 @@ const fn alignment_for(ty: Option<Type>) -> Alignment {
     match ty {
         Some(Type::Int | Type::Real | Type::Decimal | Type::Serial) => Alignment::Right,
         Some(Type::Text) | Some(Type::Bool) | Some(Type::Date) | Some(Type::DateTime)
-        | Some(Type::Blob) | Some(Type::ShortId) | None => Alignment::Left,
+        | Some(Type::ShortId) | None => Alignment::Left,
     }
 }
 
@@ -1334,7 +1334,6 @@ mod tests {
             sqlite_type: match ty {
                 Type::Int | Type::Serial | Type::Bool => "INTEGER".to_string(),
                 Type::Real => "REAL".to_string(),
-                Type::Blob => "BLOB".to_string(),
                 _ => "TEXT".to_string(),
             },
             notnull,
@@ -1361,7 +1360,6 @@ mod tests {
             Type::Bool,
             Type::Date,
             Type::DateTime,
-            Type::Blob,
             Type::ShortId,
         ] {
             assert_eq!(alignment_for(Some(ty)), Alignment::Left, "{ty:?}");