fix/macos launch (#18)

* fix: macOS Finder launch (store path, ad-hoc signing, vendored openssl)

- Store::open was resolving 'gridline.db' relative to the working directory;
  Finder/LaunchServices launches run with cwd=/ so the .expect() panicked
  (exit 101, silent 'app does nothing') before Tauri ever started. Open the
  store under app.path().app_data_dir() in setup instead (same dir as the
  demo DB), creating the dir when needed.
- Add bundle.macOS.signingIdentity "-" + hardenedRuntime false so the
  bundler ad-hoc signs the whole bundle. Previously only the inner binary
  got Xcode 16's linker-signed signature, which macOS treats as unsigned:
  quarantined downloads showed 'damaged and can't be opened', and after
  quarantine removal LaunchServices silently refused to spawn it.
- ssh2 now builds OpenSSL vendored (feature vendored-openssl): the release
  binary previously carried an absolute LC_LOAD_DYLIB to the build machine's
  /opt/homebrew/opt/openssl@3/lib, which dyld aborted on (and hardened
  runtime library-validation rejected even when present).
- README: document the macOS first-launch paths (right-click Open / xattr
  for the damaged-error case, re-run after every upgrade).
- release.yml: update SIGNING STATUS comment to reflect ad-hoc signing.

* chore: bump 0.7.8 -> 0.7.9 (release prep)

- Version sync across package.json, src-tauri/Cargo.toml, src-tauri/tauri.conf.json
- version.test.ts / bundle-config.test.ts / docs-coverage.test.ts expect 0.7.9
- README: both download tables -> v0.7.9 asset names; new v0.7.9 changelog entry;
  tag instructions -> v0.7.9; MAINTENANCE comment updated
- AGENTS.md maintenance note example -> v0.7.9
- ROADMAP: Shipped (0.7.9) section; Next up retitled (0.8.0) TBD

src-tauri/Cargo.lock

@@ -1783,7 +1783,7 @@ dependencies = [
 
 [[package]]
 name = "gridline"
-version = "0.7.8"
+version = "0.7.9"
 dependencies = [
  "chrono",
  "deadpool-postgres",
@@ -3047,6 +3047,15 @@ version = "0.1.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d05e27ee213611ffe7d6348b942e8f942b37114c00cc03cec254295a4a17852e"
 
+[[package]]
+name = "openssl-src"
+version = "300.6.1+3.6.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "46eb8fb9fb3b61ce1c0f8a026c4c1a0714d3a9e138e7fbde78753ce2babc3846"
+dependencies = [
+ "cc",
+]
+
 [[package]]
 name = "openssl-sys"
 version = "0.9.117"
@@ -3055,6 +3064,7 @@ checksum = "b47e7e6bb2c38cd930d25a23b40fa52e068c10e85f3e03a7f5ba5aaca5713695"
 dependencies = [
  "cc",
  "libc",
+ "openssl-src",
  "pkg-config",
  "vcpkg",
 ]