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.toml

@@ -1,6 +1,6 @@
 [package]
 name = "gridline"
-version = "0.7.8"
+version = "0.7.9"
 description = "An open-source, high-performance database GUI client for PostgreSQL and beyond"
 authors = ["you"]
 edition = "2021"
@@ -34,7 +34,10 @@ tokio-postgres = { version = "0.7", features = ["with-chrono-0_4", "with-uuid-1"
 sqlx = { version = "0.8", features = ["runtime-tokio", "mysql", "tls-rustls", "json"] }
 redis = { version = "0.27", features = ["tokio-comp"] }
 # async-ssh2 is not available at v0.4; using synchronous ssh2 via tokio::task::spawn_blocking per plan's fallback
-ssh2 = { version = "0.9" }
+# vendored-openssl: link OpenSSL statically so the release binary has NO
+# runtime dependency on the build machine's Homebrew openssl (@/opt/homebrew
+# absolute LC_LOAD_DYLIB — dyld aborts on user machines without it).
+ssh2 = { version = "0.9", features = ["vendored-openssl"] }
 deadpool-postgres = { version = "0.14" }
 indexmap = { version = "2", features = ["serde"] }
 tauri-plugin-keyring-store = { version = "0.2.0", default-features = false }