refactor: changed effects, add shell completions

- Extract all apply_* effect methods from screenshot.rs into dedicated
  src/effects.rs (blur, vignette, pixelate, swirl) — screenshot.rs
- Rewrite apply_blur: replace broken fastblur::gaussian_blur (horizontal-
  only box blur, backbuf dropped) with correct inline two-pass sliding-
  window box blur operating directly on Cairo surface bytes — ~10×
  faster, no ImageBuffer round-trip, no fastblur dependency
- Remove melting effect entirely (seems to be hard to implement
  properely, tried multiple itterations)
- Drop unused dependencies: fastblur, rand
- Add clap_complete dependency + --completions {bash,fish,zsh} flag,
  with CompletionShell enum in config.rs
- Fix show_* flags defaulting to true: remove default_value_t=true from
  show_media, show_battery, show_network, show_bluetooth, show_album_art,
  show_caps_lock_text — all now opt-in (matching user expectation)
- Convert peek toggle to hold: toggle_peek() → set_peek_held(held: bool),
  Press calls set_peek_held(true), new Release handler iterates all
  surfaces and calls set_peek_held(false), matching Ctrl-hold behavior
- Fix cursor rendering: increase font size 11→14 for peeked chars,
  handle cursor_position == 0 (prevent negative t wrapping to far ring
  end)
- Fix peek hit-test: use shape-aware point_in_shape() instead of simple
  circle pill/square/diamond/hexagon now detect clicks correctly within
  their area
- Remove per-frame DEBUG logs: PEEK/DOT mode in lock.rs,
  set_password_display/peek_password in render/mod.rs
- Update README: embed rustlock-effects.webp demo, remove melting
  references, correct show_* defaults and options table

.github/workflows/nightly-release.yml

@@ -14,10 +14,16 @@ jobs:
     permissions:
       contents: write
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
         with:
           fetch-depth: 0
 
+      - uses: ./.github/actions/deps
+
+      - uses: Swatinem/rust-cache@v2
+
+      - uses: dtolnay/rust-toolchain@stable
+
       - name: Set version
         id: version
         run: |
@@ -26,10 +32,19 @@ jobs:
           VERSION=$(grep -m1 '^version =' Cargo.toml | cut -d'"' -f2)
           echo "VERSION=${VERSION}-nightly.$DATE.$SHA" >> $GITHUB_OUTPUT
 
+      - name: Build release binary
+        run: cargo build --release
+
+      - name: Upload binary
+        uses: actions/upload-artifact@v4
+        with:
+          name: rustlock-${{ steps.version.outputs.VERSION }}
+          path: target/release/rustlock
+
       - name: Create nightly release
         uses: softprops/action-gh-release@v3
         with:
-          tag_name: nightly-${{ steps.version.outputs.VERSION }}
+          tag_name: ${{ steps.version.outputs.VERSION }}
           name: Nightly Build ${{ steps.version.outputs.VERSION }}
           prerelease: true
           generate_release_notes: true