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/project/mod.rs

@@ -384,7 +384,7 @@ impl Project {
     /// Build the on-disk skeleton for a fresh project: the
     /// directory itself, an empty `data/`, an empty
     /// `history.log`, a placeholder `project.yaml` with just
-    /// `version: 1` and `created_at`, and a `.gitignore`.
+    /// the current schema `version` and `created_at`, and a `.gitignore`.
     ///
     /// `playground.db` is not created here; it's created the
     /// first time `Database::open` runs against the path
@@ -401,7 +401,8 @@ impl Project {
         // schema mutation; for now we just ensure the file
         // exists and carries the version + creation timestamp.
         let yaml = format!(
-            "version: 1\nproject:\n  created_at: {}\ntables: []\nrelationships: []\n",
+            "version: {}\nproject:\n  created_at: {}\ntables: []\nrelationships: []\n",
+            crate::persistence::migrations::CURRENT_SCHEMA_VERSION,
             iso8601_now(),
         );
         write_if_missing(&path.join(PROJECT_YAML), &yaml)?;
@@ -830,7 +831,7 @@ mod tests {
 
         // YAML carries version + created_at.
         let yaml = fs::read_to_string(path.join(PROJECT_YAML)).unwrap();
-        assert!(yaml.contains("version: 1"));
+        assert!(yaml.contains("version: 2"));
         assert!(yaml.contains("created_at:"));
 
         // .gitignore matches ADR-0015.