feat: add session-aware history commands (ghistory, lhistory) (#111)

Add two new CLI commands for command history with session metadata:

- ghistory: global history across all sessions
  - ghistory N: show last N entries
  - ghistory -s <session_id>: filter by session

- lhistory: local history for current session only
  - lhistory N: show last N entries

Implementation details:
- Add session identity fields (session_id, session_tty, session_start)
  to DATA struct in CLIcore.h and CLIcore_standalone.h
- Create ~/.milk_history_log as append-only TSV file recording
  every command with: timestamp, session_id, terminal, command
- Session ID format: <processname>-<PID> (e.g., milk-12345)
- Structured log runs alongside readline history (no opt-in needed)
- Existing ~/.milk_history (readline) remains unchanged

Author: oguyon

src/cli/CLIcore/CLIcore.c

@@ -521,6 +521,9 @@ errno_t runCLI(int argc, char *argv[], char *promptstring)
     // Load persistent command history
     cli_history_load();
 
+    // Initialize structured history log
+    cli_history_log_init();
+
     // Load persistent bookmarks
     cli_bookmark_load();
 
@@ -1348,6 +1351,24 @@ void runCLI_cmd_init()
         "fhist",
         "cli_fhist()");
 
+    RegisterCLIcommand(
+        "ghistory",
+        __FILE__,
+        cli_ghistory,
+        "global history (all sessions)",
+        "[N] [-s <session_id>]",
+        "ghistory 50",
+        "cli_ghistory()");
+
+    RegisterCLIcommand(
+        "lhistory",
+        __FILE__,
+        cli_lhistory,
+        "local history (current session)",
+        "[N]",
+        "lhistory",
+        "cli_lhistory()");
+
     RegisterCLIcommand(
         "fparam",
         __FILE__,

src/cli/CLIcore/CLIcore.h

@@ -380,6 +380,13 @@ typedef struct
     int CMDexecuted;
     errno_t CMDerrstatus;
 
+    // SESSION IDENTITY
+    // =================================================
+
+    char            session_id[64];
+    char            session_tty[64];
+    struct timespec session_start;
+
     // MODULES
     // =================================================