repro_cli_support: forward reprobuild env vars to user daemon

The CLI snapshots the user's shell environment in
``daemonCarriedEnvironment()`` and ships it across the daemon protocol
so the daemon-hosted build subprocesses inherit the user's toolchain
configuration. The allowlist was missing the reprobuild-specific env
vars that ``config.nims`` and the interface-extraction nim subprocesses
read:

- REPROBUILD_USE_SYSTEM_HASH_LIBS: when "1", config.nims uses system
  libblake3 / libxxhash (-I/-L/-lblake3 / -lxxhash). Without it,
  config.nims defaults to vendored mode and ``--define:reproVendoredHash``,
  which makes ``libs/blake3/src/blake3.nim`` try to ``.compile:`` from
  ``references/mold/third-party/blake3/c/`` — the references directory
  is gitignored, so CI checkouts fail at the very first nim subprocess
  the daemon spawns ("daemon-hosted build failed: ... cannot find:
  ../../../references/mold/third-party/blake3/c/blake3.c").
- BLAKE3_PREFIX / XXHASH_PREFIX / SQLITE_PREFIX: prefix paths that
  config.nims and ``externalHashFlags`` read to discover the system
  libs.
- NIMCRYPTO_SRC / RUNQUOTA_SRC / BEARSSL_SRC: source-only dependency
  inputs config.nims registers as ``addPackagePath`` lookups so
  ``import nimcrypto`` etc. work without nimble.

This unblocks ``repro build test`` in CI under the daemon-hosted path.
Local development was unaffected because ``nix develop --command`` sets
the env vars on the CLI shell, the CLI passes them to a fresh daemon
that inherits them via fork.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: zah

libs/repro_cli_support/src/repro_cli_support.nim

@@ -7720,7 +7720,14 @@ const
     "REPROBUILD_ACTION_CACHE_ROOT", "REPROBUILD_MAX_PARALLELISM",
     "REPRO_STATS_DIR", "REPROBUILD_NO_RUNQUOTA",
     "REPROBUILD_AUTO_RUNQUOTA",
-    "REPRO_DAEMON_TEST_STATS_FLUSH_DELAY_MS"
+    "REPRO_DAEMON_TEST_STATS_FLUSH_DELAY_MS",
+    # Reprobuild's own build-time env vars consumed by config.nims and the
+    # interface-extraction nim subprocesses. Without these, config.nims
+    # defaults to vendored-hash mode and tries to compile from
+    # references/mold/, which is gitignored and so missing in CI checkouts.
+    "REPROBUILD_USE_SYSTEM_HASH_LIBS",
+    "BLAKE3_PREFIX", "XXHASH_PREFIX", "SQLITE_PREFIX",
+    "NIMCRYPTO_SRC", "RUNQUOTA_SRC", "BEARSSL_SRC"
   ]
 
   ## Well-known toolchain env vars that must also be forwarded to the daemon