feat(lang,stdlib): 64-bit long type + 64-bit Hash variants (issue #17)

Add `long`, a 64-bit signed integer primitive (i64), threaded through
codegen: llty; int<->long coercion (coerce_code/to_long) at let/assign/
return/call-args; i64 arithmetic + comparison promotion in emit_bin;
unary negate/~; print via %lld and str()/interpolation via @fn_long_str.
Editor vocabulary (syntax header, TextMate grammar, formatter, LSP)
synced; check-vocabulary green. Numeric literals stay i32 — build large
values by widening (documented on the type page).

Complete the Hash.* namespace (issue #17) with both 32- and 64-bit
algorithms: Hash.of/fnv1a/crc32/mix/combine (32-bit) and
Hash.of64/fnv1a_64/mix64 (64-bit, returning long). Deterministic and
C-free; CRC-32 (poly 0xEDB88320) and FNV vectors verified against
reference implementations.

Tests: selfhost/tests/{hash,long}.ludic. Docs: docs/language/hash/*,
type-long.md. Seed reseeded; C-free bootstrap fixpoint holds; 23
selfhost + 45 regression + 29 tooling checks green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/language/hash/hash-crc32.md

@@ -0,0 +1,28 @@
+---
+id: hash-crc32
+name: Hash.crc32
+category: hash
+kind: namespace-method
+tokens: Hash.crc32
+sig: Hash.crc32(s) -> int
+tip: CRC-32 checksum for corruption detection.
+order: 3
+ns: Hash
+member: crc32
+---
+
+The <a href="https://en.wikipedia.org/wiki/Cyclic_redundancy_check">CRC-32</a> checksum of a string's bytes — the standard IEEE 802.3 variant (reflected polynomial <code>0xEDB88320</code>), the same one used by zip, gzip and PNG. Its well-known check value: <code>Hash.crc32("123456789")</code> is <code>0xCBF43926</code>. Use it to catch accidental corruption in a save file, downloaded asset, or config blob: store the checksum alongside the data and compare on load. It detects damage, not tampering — an attacker can trivially forge a matching CRC, so it is not a security check (see the section note).
+
+Parameters:
+- `s` — the string (bytes) to checksum
+
+```ludic
+program Checksum {
+  entry {
+    let data = "save:level=3;coins=120"
+    let ck = Hash.crc32(data)     # store this next to the save; recompute on load
+    print(ck)
+    print(Hash.crc32(data) == ck) # 1 — unchanged data checks out
+  }
+}
+```