fix(scripts): use /usr/bin/env bash shebangs (NixOS has no /bin/bash)

On NixOS (and other non-FHS systems) /bin/bash does not exist, so
scripts with an absolute shebang fail to run. Switch the remaining
holdouts to /usr/bin/env bash: eleven scripts/*.sh,
test-infrastructure/run.sh, and the three Claude Code hook scripts
emitted by src/cli/cli.c (gate, session reminder, subagent reminder).

Distilled from PR #674, with parser-test coverage preserved: the
infra_parse_shell* fixtures in tests/test_pipeline.c intentionally keep
#!/bin/bash so absolute-path shebang extraction stays covered, and
tests/repro fixtures are untouched.

Also replace the GitHub-PAT-shaped fixture string flagged in the #674
thread with an obviously fake placeholder (ghp_FAKE...) that still
matches the ghp_ + 36-alnum secret detector.

Co-authored-by: Sandro Jäckel <sandro.jaeckel@gmail.com>
Signed-off-by: Martin Vogel <martin.vogel.tech@gmail.com>

scripts/benchmark-search-graph.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # benchmark-search-graph.sh — Time search_graph name_pattern= queries against a
 # codebase-memory-mcp binary to measure the regex / LIKE pre-filter performance.
 #

scripts/build.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # build.sh — Clean build of production binary (standard or with UI).
 #
 # Usage:

scripts/check-nolint-whitelist.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # Verify NOLINT(misc-no-recursion) only appears on whitelisted functions.
 WHITELIST="src/foundation/recursion_whitelist.h"
 if [ ! -f "$WHITELIST" ]; then

scripts/clean.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # clean.sh — Remove ALL build artifacts, caches, and generated files.
 #
 # Usage: scripts/clean.sh

scripts/embed-frontend.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # embed-frontend.sh — Convert built frontend assets into linkable object files.
 #
 # Usage: scripts/embed-frontend.sh <dist_dir> <output_dir>

scripts/env.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # env.sh — Shared environment detection for all build scripts.
 #
 # Sourced by test.sh, build.sh, lint.sh. Not meant to run standalone.

scripts/lint.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # lint.sh — Run all linters (clang-tidy + cppcheck + clang-format).
 #
 # Usage:

scripts/repro.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # repro.sh — Build + run the cumulative BUG-REPRODUCTION suite (test-repro).
 #
 # Unlike test.sh (the gating suite, must be GREEN), this suite is RED by design:

scripts/soak-test.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # soak-test.sh — Endurance test for codebase-memory-mcp.
 #
 # Runs compressed workload cycles: queries, file mutations, reindexes, idle periods.

scripts/test.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # test.sh — Clean build + run all C tests with ASan + UBSan.
 #
 # Usage:

scripts/vendor-grammar.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # vendor-grammar.sh: Vendor a single tree-sitter grammar into internal/cbm/vendored/grammars/<name>/
 # Usage: ./scripts/vendor-grammar.sh <repo_url> <name> [subdir]
 #   repo_url: GitHub repository URL (e.g., https://github.com/tree-sitter/tree-sitter-json)

src/cli/cli.c

@@ -2055,7 +2055,7 @@ void cbm_install_hook_gate_script(const char *home, const char *binary_path) {
         return;
     }
     (void)fprintf(f,
-                  "#!/bin/bash\n"
+                  "#!/usr/bin/env bash\n"
                   "# codebase-memory-mcp search augmenter (Claude Code PreToolUse).\n"
                   "# NOTE: the legacy filename is kept for zero-migration upgrades.\n"
                   "# Despite the name this NEVER blocks a tool call - it only adds\n"
@@ -2099,7 +2099,7 @@ static void cbm_install_session_reminder_script(const char *home) {
         return;
     }
     (void)fprintf(
-        f, "#!/bin/bash\n"
+        f, "#!/usr/bin/env bash\n"
            "# SessionStart hook: remind agent to use codebase-memory-mcp tools.\n"
            "# Installed by codebase-memory-mcp. Fires on startup/resume/clear/compact.\n"
            "cat << 'REMINDER'\n"
@@ -2187,7 +2187,7 @@ static void cbm_install_subagent_reminder_script(const char *home) {
      * backslashes, or newlines, so the JSON below is valid as written — no
      * runtime escaping (and no python3/jq dependency) is required. */
     (void)fprintf(f,
-                  "#!/bin/bash\n"
+                  "#!/usr/bin/env bash\n"
                   "# SubagentStart hook: tell subagents to use codebase-memory-mcp tools.\n"
                   "# Installed by codebase-memory-mcp. Fires when any subagent is spawned.\n"
                   "# SubagentStart injects context via JSON additionalContext, not plain stdout.\n"

test-infrastructure/run.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # Local CI — test all platforms before pushing.
 #
 # Coverage:

tests/test_pipeline.c

@@ -4669,7 +4669,7 @@ TEST(envscan_secret_value_exclusion) {
     write_temp_file(
         tmpdir, "deploy.sh",
         "#!/bin/bash\n"
-        "export GH_URL=\"https://ghp_abcdefghijklmnopqrstuvwxyz1234567890@github.com/repo\"\n"
+        "export GH_URL=\"https://ghp_FAKEFAKEFAKEFAKEFAKEFAKEFAKEFAKEFAKE@github.com/repo\"\n"
         "export NORMAL_ENDPOINT=\"https://api.example.com/orders\"\n");
 
     cbm_env_binding_t bindings[32];