chore: bump version to 1.0.8

SQLITE_AI_VERSION is the single source of truth for a release: the workflow
reads it via `make version`, tags from it, and rewrites Package.swift's URL and
checksum afterwards. Bumping it is what makes the release job publish rather
than warn that the version matches the latest release.

Patch bump, matching the recent fix releases (#29, #30, #31). The changes on
this branch are bug fixes, though note one deliberate behaviour change: calls
that previously returned '' or crashed now fail with SQLITE_MISUSE.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ks738YbgnnJBio2wLtpbAJ

Author: andinux

src/sqlite-ai.h

@@ -24,7 +24,7 @@
 extern "C" {
 #endif
 
-#define SQLITE_AI_VERSION "1.0.7"
+#define SQLITE_AI_VERSION "1.0.8"
 
 SQLITE_AI_API int sqlite3_ai_init (sqlite3 *db, char **pzErrMsg, const sqlite3_api_routines *pApi);