feat(seed): fake-data generation library + fake dependency (ADR-0048 P1.1)

The pure generation half of `seed` — no command wiring yet:
- src/seed/: ColumnSpec + Generator model and a seeded StdRng; the
  type-gated name-heuristic catalogue (D7) with documented
  false-positive guards; table-context name disambiguation (D11);
  identifier (D10) and enum-ish (D12) detection; per-type + bounded-date
  generators (D8); the hand-rolled product generator (D9); and PickFrom
  for IN-CHECK / enum lists.
- Adds the `fake` crate (v5, default features). Verified: single rand
  0.10.1 (no duplication), determinism via one seeded StdRng driving
  both fake and the hand-rolled generators, security-clean across
  osv/grype/trivy.
- ADR-0048 D3 updated to record the dependency verification.

32 Tier-1 tests (exact-value via fixed --seed); 1673 lib tests pass,
clippy all-targets clean.

Cargo.lock

@@ -419,6 +419,12 @@ dependencies = [
  "syn 2.0.117",
 ]
 
+[[package]]
+name = "deunicode"
+version = "1.6.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "abd57806937c9cc163efc8ea3910e00a62e2aeb0b8119f1793a978088f8f6b04"
+
 [[package]]
 name = "diff"
 version = "0.1.13"
@@ -518,6 +524,17 @@ dependencies = [
  "num-traits",
 ]
 
+[[package]]
+name = "fake"
+version = "5.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ea6be833b323a56361118a747470a45a1bcd5c52a2ec9b1e40c83dafe687e453"
+dependencies = [
+ "deunicode",
+ "either",
+ "rand 0.10.1",
+]
+
 [[package]]
 name = "fallible-iterator"
 version = "0.3.0"
@@ -1527,6 +1544,7 @@ dependencies = [
  "crossterm",
  "csv",
  "directories",
+ "fake",
  "futures-util",
  "gethostname",
  "insta",