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/requirements.md

@@ -404,7 +404,7 @@ since ADR-0027.)
   referenced column), then `ALTER TABLE … ALTER COLUMN TYPE` (4f —
   runtime-decomposed to `change_column_type` with `ForceConversion`, the
   §7 advanced policy: lossy converts with a note, incompatible + static
-  refusals (`↔ blob`, non-`int → serial`) refuse, `int → serial` allowed;
+  refusals (non-`int → serial`) refuse, `int → serial` allowed;
   the internal-`__rdbms_*` guard folded into `do_change_column_type`),
   then `ALTER TABLE` add/drop constraint + add FK (4g — `ADD [CONSTRAINT
   <name>] (CHECK | UNIQUE | FOREIGN KEY)` + `DROP CONSTRAINT <name>`;
@@ -430,7 +430,7 @@ since ADR-0027.)
   refused with an engine-neutral message naming the construct.
   Implementation pending.)*
 - [x] **Q3** User-facing simplified types map transparently to
-  SQLite STRICT types in generated DDL. *(All ten types implemented
+  SQLite STRICT types in generated DDL. *(All nine types implemented
   and tested.)*
 - [x] **Q4** Supported SQL subset specification — **ADR-0030**.
   Advanced mode is a standard-SQL surface, engine-neutral; the
@@ -462,10 +462,11 @@ since ADR-0027.)
 
 ## Type system (per ADR-0005)
 
-- [x] **T1** All ten user-facing types implemented: `text`,
-  `int`, `real`, `decimal`, `bool`, `date`, `datetime`, `blob`,
+- [x] **T1** All nine user-facing types implemented: `text`,
+  `int`, `real`, `decimal`, `bool`, `date`, `datetime`,
   `serial`, `shortid`. *(Mapping to SQLite STRICT covered by
-  ADR-0005; FK target type rule by ADR-0011.)*
+  ADR-0005; FK target type rule by ADR-0011; `blob` dropped by
+  ADR-0005 Amendment 2.)*
 - [x] **T2** `shortid` generation: base58, 10–12 characters,
   omits ambiguous characters; generated client-side at insert.
   *(Implemented per ADR-0014; auto-fills omitted shortid