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/0030-advanced-mode-sql-surface.md

@@ -172,7 +172,7 @@ representation; the SQL surface does not round-trip through it.
 
 ### 5. Type vocabulary — the playground's, not the engine's
 
-Advanced-mode DDL uses the playground's own ten-type
+Advanced-mode DDL uses the playground's own nine-type
 vocabulary (ADR-0005). There is **no fallback to engine
 storage types**: a column created in advanced mode is a
 first-class `serial` / `decimal` / `date` / … exactly as a
@@ -373,7 +373,7 @@ ADR when taken up (ADR-0026-style).
 - ADR-0002 — the engine is an implementation detail; "no
   engine name in user-facing strings" — §7 extends it.
 - ADR-0003 — the simple / advanced mode model this builds on.
-- ADR-0005 — the ten-type vocabulary advanced DDL uses (§5).
+- ADR-0005 — the nine-type vocabulary advanced DDL uses (§5).
 - ADR-0009 — the DSL conventions; the DSL stays usable in
   advanced mode.
 - ADR-0012 / ADR-0013 — the metadata tables the `Command` core