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).

docs/adr/0035-advanced-mode-sql-ddl.md

@@ -58,7 +58,7 @@ Two things from the earlier phases shape this one:
    executed as-is, the engine would make the table, but the
    playground would lose what the user meant: that `id` is `serial`,
    that a `REFERENCES` clause is a *named relationship*, that `STRICT`
-   applies, that the ten-type vocabulary governs. Recovering that
+   applies, that the nine-type vocabulary governs. Recovering that
    needs the parsed statement either way.
 
 ADR-0030 §4 said "DDL → a `Command` … run the typed executor." That
@@ -92,7 +92,7 @@ mode. Unlike the DML `Sql*` commands they **execute structurally**:
 the handler reads the parsed structure and performs the schema change
 through the playground's metadata-maintaining machinery — writing
 `__rdbms_playground_columns` / `__rdbms_playground_relationships`,
-applying `STRICT`, using the ten-type vocabulary — so an
+applying `STRICT`, using the nine-type vocabulary — so an
 advanced-mode-created object is a first-class playground object,
 identical to a simple-mode-created one (ADR-0030 §5).
 
@@ -772,5 +772,5 @@ honouring it is not the lesson.
 - **ADR-0017** — the column type-change classification §7 shares.
 - **ADR-0029** — column constraints; **ADR-0025** — indexes;
   **ADR-0011** — FK column-type compatibility; **ADR-0005** — the
-  ten-type vocabulary.
+  nine-type vocabulary.
 - **ADR-0006** — undo; each DDL statement is one undo step (§10).