iOS SQLite compiled with exqlite's defines, so FTS5 works on device (MOB-487)

[GenericJam]

Fixes MOB-487 (iOS half and the single definition; Android templates in GenericJam/mob_new#104, which must merge first: this PR's sync test reads mob_new master's templates in CI).

mob compiled exqlite's SQLite amalgamation with only -DSQLITE_THREADSAFE=1, so on the phone SQLite had no FTS5 (no such module: fts5) and none of exqlite's other features, while the host NIF (exqlite's Makefile) had them.

• MobDev.Exqlite.defines/0 / cflags/0: exqlite's Makefile CFLAGS += -D… lines, verbatim and in order. The one definition for every mob_dev build of the NIF:
  • iOS simulator sqlite3_nif.so (cross_compile_exqlite_nif_sim)
  • iOS device sqlite3_nif.a, both objects (cross_compile_exqlite_nif_device)
  • mix mob.release --ios (release_device.sh, $SQLITE_CFLAGS)
• MobDev.ExqliteTest: the set includes FTS5; equals the locked exqlite's Makefile set (exqlite added as a test-only dep with compile: false, app: false: source only, never built or loaded); equals the list in mob_new's Android build.zig.eex and CMakeLists.txt.eex (read via MobDev.Adopt.Generator.templates_root/1, as the -dead_strip test does).
• CHANGELOG: Fixed + Upgrading (the Android lines existing apps add).

Verified with a throwaway mix mob.new --blank --local app (path deps on these worktrees) whose screen runs CREATE VIRTUAL TABLE t USING fts5(x), an INSERT and a MATCH through Exqlite:

	before	after
Android emulator (arm64)	FTS5 ERROR "no such module: fts5"	FTS5 OK rows=[["in the beginning"]]
iOS simulator (iOS 27)	FTS5 ERROR "no such module: fts5"	FTS5 OK rows=[["in the beginning"]]

iOS device path (no physical iPhone): compiled sqlite3.c with the iphoneos SDK and MobDev.Exqlite.cflags() exactly as cross_compile_exqlite_nif_device does; the object carries the FTS5 module (345 fts5 symbols, sqlite3RtreeInit). release_device.sh passes bash -n and both exqlite compiles use $SQLITE_CFLAGS.

Note: the set includes SQLITE_DQS=0, so the device, like the host, rejects double-quoted string literals.

[GenericJam]

Review: reviewer subagent (Codex rate-limited until 17:26 today): MERGE. First pass: one should-fix (ExqliteTest read mob_new templates through templates_root/1, which can hit an installed archive or stale ~/code/mob_new) and one nitpick (test-only exqlite dep pulls db_connection); both addressed in f5912ba. Re-review: MERGE, no findings. Companion GenericJam/mob_new#104 merged first; CI tests green on f5912ba (run 38808121786, 3036 tests, 0 failures, sync test ran against mob_new master).