feat: add repo planning/binary repo support and Meson build integration

- add repos.toml source/binary repo configuration with arch overrides and priorities
- add dependency planner/execution plan flow with interactive provider selection and --yes support
- expand binary repo DB metadata (sha512, dependencies, file lists) and repo owns/search helpers
- add rootfs-scoped fd locking and minisign detached signing/verification helpers
- add Meson build/test support for the project with builddir-local CARGO_HOME/CARGO_TARGET_DIR
- install contrib example configs into sysconfdir (/etc/depot.d layout) via Meson
- improve builder env handling (sanitized PATH, tool env passthrough, CXXFLAGS support)
- support += appends in package specs and add build.flags.cxxflags parsing
- prompt for git credentials when private repo auth is required
- update docs/examples and dependency setup (system libs, zstdmt, tempfile pin)

src/staging/mod.rs

@@ -219,7 +219,7 @@ fn auto_strip_elf_files(destdir: &Path) -> Result<usize> {
         }
 
         let status = Command::new("strip")
-            .arg("--strip-unneeded")
+            .arg("--strip-debug")
             .arg(path)
             .status()
             .with_context(|| {
@@ -278,7 +278,7 @@ fn compress_manpages_zstd(destdir: &Path) -> Result<usize> {
         let out_file = fs::File::create(&tmp_path)
             .with_context(|| format!("Failed to create {}", tmp_path.display()))?;
 
-        let mut encoder = zstd::stream::write::Encoder::new(out_file, 22)
+        let mut encoder = zstd::stream::write::Encoder::new(out_file, 19)
             .with_context(|| format!("Failed to start zstd encoder for {}", path.display()))?;
         io::copy(&mut input, &mut encoder)
             .with_context(|| format!("Failed to compress {}", path.display()))?;