feat: restructure repo, borrow checker, expanded stdlib

- Reorganize repository to Rust-style layout:
  compiler/bootstrap/  compiler/selfhost/  compiler/tests/
  library/std/  library/runtime/  tests/  tools/
- Add buxs/ Windows-compatible project root
- Add borrow checker tests and implement:
  - Alias analysis (double mutable borrow detection)
  - Use-after-move detection for own T
- Expand standard library:
  - Std::Os: Args, Env, Cwd, Chdir
  - Std::Time: NowMs, NowUs, SleepMs
  - Std::Process: Run, Output
  - Std::Io: PrintInt64 (fixes 32-bit truncation bug)
- Add examples: os_time.bux, process.bux
- Fix PrintInt to use int64_t in C runtime

compiler/selfhost/manifest.bux

@@ -0,0 +1,89 @@
+// manifest.bux — Manifest parser for bux.toml files
+// Parses package metadata: name, version, type, build output.
+module Manifest {
+
+extern func bux_strlen(s: String) -> uint;
+
+// ---------------------------------------------------------------------------
+// Manifest struct
+// ---------------------------------------------------------------------------
+struct Manifest {
+    name: String;
+    version: String;
+    pkgType: String;
+    output: String;
+}
+
+// ---------------------------------------------------------------------------
+// Simple TOML parser (handles [Package] and [Build] sections)
+// ---------------------------------------------------------------------------
+
+func Manifest_Parse(content: String) -> Manifest {
+    var m: Manifest;
+    m.name = "";
+    m.version = "0.1.0";
+    m.pkgType = "bin";
+    m.output = "Bin";
+
+    if String_Eq(content, "") { return m; }
+
+    var currentSection: String = "";
+    let count: uint = String_SplitCount(content, "\n");
+    var i: uint = 0;
+    while i < count {
+        let line: String = String_SplitPart(content, "\n", i);
+
+        // Skip empty lines and comments
+        if String_Eq(line, "") { i = i + 1; continue; }
+        if String_StartsWith(line, "#") { i = i + 1; continue; }
+
+        // Section header: [Section]
+        if String_StartsWith(line, "[") {
+            if String_StartsWith(line, "[Package]") {
+                currentSection = "Package";
+            } else if String_StartsWith(line, "[Build]") {
+                currentSection = "Build";
+            } else {
+                currentSection = "";
+            }
+            i = i + 1; continue;
+        }
+
+        // Key = Value
+        let eqCount: uint = String_SplitCount(line, "=");
+        if eqCount >= 2 {
+            let key: String = String_Trim(String_SplitPart(line, "=", 0));
+            let rawVal: String = String_Trim(String_SplitPart(line, "=", 1));
+
+            // Strip quotes from value
+            var val: String = rawVal;
+            if String_StartsWith(val, "\"") && String_EndsWith(val, "\"") {
+                let vlen: uint = bux_strlen(val);
+                if vlen >= 2 {
+                    val = String_Slice(val, 1, vlen - 2);
+                }
+            }
+
+            if String_Eq(currentSection, "Package") {
+                if String_Eq(key, "Name") { m.name = val; }
+                if String_Eq(key, "Version") { m.version = val; }
+                if String_Eq(key, "Type") { m.pkgType = val; }
+            } else if String_Eq(currentSection, "Build") {
+                if String_Eq(key, "Output") { m.output = val; }
+            }
+        }
+        i = i + 1;
+    }
+
+    return m;
+}
+
+// ---------------------------------------------------------------------------
+// Load manifest from file
+// ---------------------------------------------------------------------------
+
+func Manifest_Load(path: String) -> Manifest {
+    let content: String = ReadFile(path);
+    return Manifest_Parse(content);
+}
+}