feat: add calculator and unit conversion

README.md

@@ -30,9 +30,9 @@ Open `Package.swift` in Xcode to edit the project. Use the bundled app above to
 
 ## Controls
 
-- Type to filter applications; the first match is selected automatically.
+- Type to filter applications, calculate an expression, or convert units; the first result is selected automatically.
 - Up/Down or Control-K/Control-J changes the selection without leaving search or modifying its text.
-- Return, keypad Enter, the Open Application button, or a double-click opens the selection.
+- Return, keypad Enter, the footer button, or a double-click opens the selected application or copies a calculator answer and dismisses the launcher.
 - Command-K or the bottom-right Actions button opens a searchable selector for the selected application. **Open** is first and selected by default. Up/Down or Control-K/Control-J selects an action; Return executes it. Escape closes the selector and returns focus to search.
 - Escape or Command-W dismisses the launcher and restores the previously active application. Switching focus away dismisses it without stealing focus back.
 - Reopen from Finder to show it again with an empty search. Dismissal leaves the process running; Command-Q quits it.
@@ -75,6 +75,31 @@ Background discovery preserves the selected application even if its row changes.
 
 Applications with identical display names show a muted containing-folder hint beside the name. Copies sharing the same folder show their full application bundle paths instead. Home paths abbreviate to `~`, and long hints truncate in the middle. Unique names have no hint; locations are recalculated whenever discovery refreshes.
 
+## Calculator and unit conversion
+
+Type directly into search, as with [Raycast's calculator](https://manual.raycast.com/calculator). A recognized expression or conversion replaces application results with one **Calculator** row. Return, keypad Enter, double-click, or **Copy Answer** copies the displayed answer and dismisses the launcher, restoring the previously active application. Conversion answers include the destination unit. Application actions are disabled for calculator results; calculations do not affect launch ranking.
+
+Arithmetic supports `+`, `-`, `*` (also `x` or `×`), `/` (also `÷`), parentheses, scientific notation, and right-associative `^` powers. Powers bind more tightly than unary signs: `-2^2` is `-4`, while `(-2)^2` is `4`. Functions are `sqrt`, `abs`, `round`, `floor`, `ceil`, `sin`, `cos`, `tan`, `log` (base ten), and `ln`; use parentheses around their arguments. Trigonometric arguments are radians; constants are `pi`/`π` and `e`. A trailing `%` divides by 100; `%` before an unsigned operand is remainder, and `mod` accepts signed operands. Percentage queries such as `52% of 900` and `20% off 80` also work.
+
+Convert with `<expression> <source unit> to <target unit>`; `in` and `as` also work. Spaces between numbers and units are optional, and most units accept abbreviations and singular/plural English names.
+
+| Unit family | Supported units | Example query |
+| --- | --- | --- |
+| Length | mm, cm, m, km, in, ft, yd, mi | `10ft in m` |
+| Mass | mg, g, kg, oz, lb | `1 kg to pounds` |
+| Temperature | Celsius, Fahrenheit, Kelvin | `32 f to c` |
+| Volume | mL, L, US teaspoon, tablespoon, fluid ounce, cup, pint, quart, gallon | `1 cup to fl oz` |
+| Duration | milliseconds, seconds, minutes, hours, days, weeks | `2 hours in minutes` |
+| Speed | m/s, km/h, mph | `60 mph to km/h` |
+| Area | cm², m², km², in², ft²; also `square` names | `144in² to ft²` |
+| Data | bits/bytes, decimal kilo/mega/giga/tera and binary kibi/mebi/gibi/tebi | `1 GiB to MiB` |
+
+Data abbreviations distinguish lowercase `b` (bits) from uppercase `B` (bytes): `8b to B` gives `1 B`. Decimal `KB` is 1,000 bytes; binary `KiB` is 1,024. Culinary volumes use US customary measures, not imperial measures or the 240 mL legal cup.
+
+All calculation is offline, with no added dependencies or script evaluation. Output uses a decimal point and up to 12 significant digits; physical units generally use Foundation's native conversion precision, with exact defining Fahrenheit ratios and consistent US customary volume subdivisions. Division by zero, invalid function domains, nonfinite results, and incompatible unit families show a non-copyable error. Ordinary app names, standalone numeric literals, incomplete expressions, and unsupported syntax remain application searches. Input is bounded to 512 UTF-8 bytes and recursive parser depth below 16 to keep live search safe.
+
+This is arithmetic and physical/data unit conversion, not full Raycast parity: currency rates, calendar/date/time-zone calculations, design units, and unrestricted natural-language math are not supported.
+
 ## Application actions and uninstall
 
 Select an application and open **Actions ⌘K**. **Open** is the first, default-selected action and uses the same launch path, successful-launch history tracking, dismissal, and error reporting as Return in the application list. Filtering resets selection to the first matching action; an empty result does nothing on Return. Up/Down or Control-K/Control-J navigates actions without changing the selected application.
@@ -112,7 +137,7 @@ The brown tint is 35% opaque over an active, behind-window `NSVisualEffectView`
 AppKit still provides text editing, table navigation, scrolling, application icons, controls, menus, fonts, and visual-effect materials. The background uses cached native radial gradients that fade to transparent: static soft blobs, without animations, timers, image assets, blur filters, or third-party UI dependencies. Decorative drawing does not intercept clicks. Increased-contrast settings strengthen the selection outline, and text colors are tuned for readability across the glows and selection.
 
 - `Sources/Conjure`: application lifecycle, launcher, Settings, contextual actions and uninstall review windows, and application launching.
-- `Sources/ConjureKit`: filesystem discovery, search ranking, launch history, global shortcut registration, launcher alignment geometry, associated-file discovery, and journaled uninstall/recovery.
-- `Tests/ConjureKitTests`: deterministic discovery, ranking, history, shortcut validation, alignment boundaries, installation safety, and uninstall failure/recovery checks.
+- `Sources/ConjureKit`: filesystem discovery, search ranking, launch history, calculator and unit conversion, global shortcut registration, launcher alignment geometry, associated-file discovery, and journaled uninstall/recovery.
+- `Tests/ConjureKitTests`: deterministic discovery, ranking, history, calculator precedence/conversion/error boundaries, shortcut validation, alignment boundaries, installation safety, and uninstall failure/recovery checks.
 
 The launcher uses Apple's [visual-effect materials](https://developer.apple.com/documentation/appkit/nsvisualeffectview), [table row selection drawing](https://developer.apple.com/documentation/appkit/nstablerowview/drawselection(in:)), [application launching](https://developer.apple.com/documentation/appkit/nsworkspace/openapplication(at:configuration:completionhandler:)), and [reopen lifecycle](https://developer.apple.com/documentation/appkit/nsapplicationdelegate/applicationshouldhandlereopen(_:hasvisiblewindows:)).