Improve accessibility labels for workout controls

[eltahirsami]

Proposed Changes

• Added increase and decrease localization keys.
• Added accessibility tooltips to repetition increment/decrement buttons.
• Added accessibility tooltips to weight increment/decrement buttons.
• Improved screen-reader support for icon-only workout controls.

Related Issue(s)

Closes #1107

Please check that the PR fulfills these requirements

• Tests for the changes have been added (for bug fixes / features)
• Set a 100-character limit to avoid white space diffs (run dart format .)

This PR improves accessibility for workout logging controls by adding descriptive tooltips to the increment and decrement buttons used for repetitions and weight inputs. These tooltips provide meaningful labels for screen readers and follow the project's existing IconButton.tooltip pattern.

[rolandgeider]

merged, thanks