fix(hint): correct H2 corpus errors + add parse guard (handoff-71)

Semantic verification pass over the tier-3 `hint` corpus (ADR-0053).
Four content errors corrected in src/friendly/strings/en-US.yaml:

- cmd.create_table: the example `with pk id(serial), name(text),
  email(text)` declares a 3-column COMPOUND primary key, not a PK
  plus regular columns (every `with pk` column is a key member,
  ADR-0005). Rewritten to a single-column PK + `add column` for the
  rest; what/concept aligned.
- cmd.save: `save as my-shop` does not parse — `save as` takes no
  inline name, it opens a path-entry prompt. Example -> `save as`;
  what no longer implies inline naming; added a temp-vs-named concept.
- cmd.import: target `shop-copy` does not parse — the `as <target>`
  slot is a NewName ident that rejects hyphens. -> `shop_copy`.
- err.foreign_key.child_side: dropped the bogus `on delete set
  null/cascade` remedy — that governs the parent direction; a
  child-side violation is fixed by inserting the parent first
  (matches the tier-1 hint).

Adds every_cmd_hint_example_parses_in_its_mode — a catalog-driven
guard that parses every hint.cmd.* example in its taught mode,
backstopping syntactic drift (it caught the save and import errors).
Registers the new hint.cmd.save.concept key.

docs: drop two stale "deferred" entries from CLAUDE.md — project
storage (export/import, --resume, input history, migration scaffold)
and m:n convenience (C4) are all implemented (ADR-0015/0045); record
the verification pass on requirements.md H2.

CLAUDE.md

@@ -37,9 +37,9 @@ Current decisions at a glance (each backed by an ADR):
   simple to advanced (ADR-0003). No other sigils.
 - **Project format:** `project.yaml` + `data/<table>.csv` +
   `history.log`; `playground.db` is a derived artifact (ADR-0004,
-  amended by ADR-0015). Implemented through Iteration 4 +
-  cleanup; export/import (Iter 5) and migration framework /
-  --resume / persistent input history (Iter 6) pending.
+  amended by ADR-0015). Fully implemented (ADR-0015 Iterations
+  1–6): export/import, `--resume`, persistent input history, and
+  the migration framework scaffold are all done.
 - **Project storage runtime:** every command persists through to
   db + yaml + csv + history.log in one execution context, gated
   by the combined db persistence logic; commit-db-last ordering
@@ -335,16 +335,8 @@ all of `target/`, forcing a full from-scratch rebuild).
 These are explicitly tracked (mostly in `requirements.md`) but
 not yet implemented:
 
-- **Project storage** (track 2): largely implemented through
-  Iteration 4 + cleanup pass + safety hardening (Iterations
-  1–4 of ADR-0015). Pending pieces: `export` / `import` (Iter
-  5), `--resume` + persistent input history hydration +
-  migration framework scaffold (Iter 6).
 - **Modify relationship** (C3a): drop+add covers the use case
   today.
-- **m:n convenience** (C4): auto-generates a junction table
-  with appropriate FKs — depends on relationships being solid
-  (they are).
 - **Strong syntax-help in parse errors** (H1a): point users at
   missing keywords/clauses rather than the unexpected
   character. *(H1 — the friendly **database**-error layer — is