chore(deps): bump Grant pin to 70ac8be (multi-tenancy, raw SQL, parity, Int64 count)

[crimson-knight]

Bumps the Grant pin in amber new, the native app generator, and templates/app/shard.yml.ecr from 2665a978 to 70ac8beaa172f03c389bacaff06cd8f3c520805c (crimson-knight/grant#46, which contains 2665a978).

Grant at that commit adds row-level and PostgreSQL schema-per-tenant multi-tenancy, bound raw SQL (find_by_sql, connection.exec_query, select_*), and fixes for 53 audit findings and a crystal-conventions review. Its whole suite passes on SQLite, crystal-alpha, PostgreSQL, and MySQL. Its runtime db dependency is now a plain 0.14.0 version backed by a checksum lock. Generated apps therefore resolve Grant alongside the pg, mysql, and sqlite3 drivers without a seeded lock.

Toolchain: amber new prefers shards-alpha when it is on PATH, because it writes a checksum-verified shard.lock. Otherwise it falls back to shards. Specs cover both selections. The native Makefile fallback is unchanged from main.

Verification:

• crystal-alpha spec: 414 examples, 0 failures (with bin/amber-lsp built as CI does).
• The SQLite web smoke test passes both with shards-alpha available and with it hidden. The generated app's specs pass (1 + 12 examples).
• A fresh PostgreSQL scaffold installs and builds.
• A native scaffold passes shards-alpha install --frozen.
• dep-pin-audit reports the same six root-manifest findings as main, and no new ones.

Merge crimson-knight/grant#46 with a merge commit, not a squash, so that 70ac8be stays on Grant's main.

[crimson-knight]

Updated to Grant 039b29468e3a1b853d9e16ba9d0738c12ea1ee23. That commit fixes Grant's runtime db pin, so the seeded shard.lock workaround is removed. Generated apps now resolve with a plain install. amber new prefers shards-alpha, which writes a checksum lock, and falls back to shards; specs cover both.

Verification: crystal-alpha spec 414 examples, 0 failures. The SQLite smoke passes with and without shards-alpha on PATH. The PostgreSQL scaffold builds, and the native scaffold passes --frozen.

[crimson-knight]

Updated the Grant pin to 70ac8beaa172f03c389bacaff06cd8f3c520805c (count APIs now return Int64). Generated app code has no Int32 count assumptions. crystal-alpha spec: 414 examples, 0 failures. The SQLite smoke passes with shards-alpha available and with it hidden.