fix(blob): #516 - fix 32-bit truncation in BLOB ID round-trip + legacy compat

[satwareAG-ironMike]

Summary

Two critical bugs found by code review before v13.0.1 release. Both cause silent data corruption for BLOB IDs with low > 0xFFFF.

Bug 1: _php_fbird_string_to_quad truncates 32-bit low part to 16 bits

fbird_blobs.c:225: cast was (ISC_USHORT)low_part — truncates 32-bit ISC_ULONG to 16 bits. The #516 fix changed the variable type and sscanf format but forgot to update the cast on the assignment line.

// Before (broken — truncates to 16 bits):
qd->gds_quad_low = (ISC_USHORT)low_part;

// After (correct — full 32-bit):
qd->gds_quad_low = (ISC_ULONG)low_part;

Bug 2: BlobId::fromString() drops lower 16 bits of hex-format input

src/Firebird/BlobId.php:140: substr($hex, 8, 4) reads only 4 hex digits (16 bits) instead of 8 (32 bits). The #516 fix changed the output format (%08X) but not the input parsing. Test blessed the buggy output.

// Before (broken — drops lower 16 bits):
$low = hexdec(substr($hex, 8, 4));  // 2345 from abcdef0123456789

// After (correct — full 32 bits):
$low = hexdec(substr($hex, 8, 8));  // 23456789 from abcdef0123456789

Issue 3: Procedural binding rejects 13-char BLOB IDs (asymmetric with OOP)

fbird_query_bind.c:929/1043, fbird_batch.c:560/741 used exact Z_STRLEN_P != BLOB_ID_LEN (17) check, rejecting legacy 13-char IDs from v13.0.0. Users upgrading could not bind stored 13-char IDs — silently treated as blob content (data corruption).

Fix: Accept both BLOB_ID_LEN (17) and BLOB_ID_LEN_LEGACY (13). _php_fbird_string_to_quad() already parses both via %x:%x.

ISC_QUAD structure (verified across FB3/FB4/FB5)

gds_quad_high: ISC_LONG  (32-bit signed)
gds_quad_low:  ISC_ULONG (32-bit unsigned)

17-char format (8+1+8 hex) is correct for ALL Firebird versions (3.0, 4.0, 5.0+).

Cosmetic fixes

• fbird_batch.c:554: removed duplicate comment block + stale 13-char example
• BlobId.php: updated stale docblocks (13→17 char format)
• php_fbird_includes.h: added BLOB_ID_LEN_LEGACY constant

Verification

CI-exact environment (php:8.4-cli-bookworm + official FB4 tarball):

• tests/blobid_001.phpt PASS (FB4 + FB5)
• tests/003.phpt PASS (FB4 + FB5)
• tests/issue119.phpt PASS
• tests/issue307_trans_start_nullable_options.phpt PASS
• tests/transaction_default_slot.phpt PASS

Found by: v13.0.1 release readiness code review