Harden deployment and fix PEN-01

- Fix Bearer token extraction to validate prefix (PEN-01)
- Add TestExtractBearerFromRequest covering PEN-01 edge cases
- Fix flaky TestRenewToken timing (2s → 4s lifetime)
- Move default config/install paths to /srv/mcias
- Add RUNBOOK.md for operational procedures
- Update AUDIT.md with penetration test round 4

Security: extractBearerFromRequest now uses case-insensitive prefix
validation instead of fixed-offset slicing, rejecting non-Bearer
Authorization schemes that were previously accepted.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

dist/mcias.conf.example

@@ -1,12 +1,12 @@
 # mcias.conf — Reference configuration for mciassrv
 #
-# Copy this file to /etc/mcias/mcias.conf and adjust the values for your
+# Copy this file to /srv/mcias/mcias.toml and adjust the values for your
 # deployment. All fields marked REQUIRED must be set before the server will
 # start. Fields marked OPTIONAL can be omitted to use defaults.
 #
 # File permissions: mode 0640, owner root:mcias.
-#   chmod 0640 /etc/mcias/mcias.conf
-#   chown root:mcias /etc/mcias/mcias.conf
+#   chmod 0640 /srv/mcias/mcias.toml
+#   chown root:mcias /srv/mcias/mcias.toml
 
 # ---------------------------------------------------------------------------
 # [server] — Network listener configuration
@@ -26,11 +26,11 @@ listen_addr = "0.0.0.0:8443"
 # REQUIRED. Path to the TLS certificate (PEM format).
 # Self-signed certificates work fine for personal deployments; for
 # public-facing deployments consider a certificate from Let's Encrypt.
-tls_cert = "/etc/mcias/server.crt"
+tls_cert = "/srv/mcias/server.crt"
 
 # REQUIRED. Path to the TLS private key (PEM format).
 # Permissions: mode 0640, owner root:mcias.
-tls_key = "/etc/mcias/server.key"
+tls_key = "/srv/mcias/server.key"
 
 # OPTIONAL. IP address of a trusted reverse proxy (e.g. nginx, Caddy, HAProxy).
 # When set, the rate limiter and audit log extract the real client IP from the
@@ -55,7 +55,7 @@ tls_key = "/etc/mcias/server.key"
 # REQUIRED. Path to the SQLite database file.
 # The directory must be writable by the mcias user. WAL mode is enabled
 # automatically; expect three files: mcias.db, mcias.db-wal, mcias.db-shm.
-path = "/var/lib/mcias/mcias.db"
+path = "/srv/mcias/mcias.db"
 
 # ---------------------------------------------------------------------------
 # [tokens] — JWT issuance policy
@@ -113,13 +113,13 @@ threads = 4
 # database on first run and reused on subsequent runs so the same passphrase
 # always produces the same master key.
 #
-# Set the passphrase in /etc/mcias/env (loaded by the systemd EnvironmentFile
+# Set the passphrase in /srv/mcias/env (loaded by the systemd EnvironmentFile
 # directive). See dist/mcias.env.example for the template.
 passphrase_env = "MCIAS_MASTER_PASSPHRASE"
 
 # Option B: Key file mode. The file must contain exactly 32 bytes of raw key
-# material (AES-256). Generate with: openssl rand -out /etc/mcias/master.key 32
+# material (AES-256). Generate with: openssl rand -out /srv/mcias/master.key 32
 # Permissions: mode 0640, owner root:mcias.
 #
 # Uncomment and comment out passphrase_env to switch modes.
-# keyfile = "/etc/mcias/master.key"
+# keyfile = "/srv/mcias/master.key"