fix(theme): solid per-theme hyprland borders, matching legacy

v1 forced an accent→accentAlt 45deg gradient on every theme's window
border; the legacy identity themes all used a *solid* border — accent for
nord/retro-82/lumon, the text tone for kanagawa/summer-day/summer-night.

Add a palette-resolved `border` field ({active, inactive}, each a palette
key or literal hex) to the theme schema with accent/overlay defaults in
theme.nix, consume it solid in hyprland.nix, and declare it in every
preset (and the live state). Declaring it everywhere is required because
`nomarchy-theme-sync apply` deep-merges presets — an omitted field would
stick across switches, like colors already are fully specified per theme.

All six identity themes resolve to their exact legacy active border
(verified: nord #81a1c1, retro-82 #faa968, lumon #f2fcff, kanagawa
#dcd7ba, summer-night #d3c6aa, summer-day #5c6a72). nix flake check passes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -379,10 +379,13 @@ close · `SUPER+1..9` workspaces · `Print` region screenshot.
 - ✓ **Enable nix-ld by default:** `programs.nix-ld.enable` is on distro-wide
   (`modules/nixos/default.nix`), so prebuilt/foreign dynamically-linked
   binaries run out of the box.
-- **Hyprland border colors off for some themes:** the active/inactive border
-  colors don't match the legacy branch for several themes — audit
-  `col.active_border`/`col.inactive_border` generation in
-  `modules/home/hyprland.nix` against legacy.
+- ✓ **Hyprland border colors off for some themes:** the cause was v1
+  forcing an `accent→accentAlt` gradient on every theme; legacy used a
+  *solid* border (accent for nord/retro-82/lumon, the text tone for
+  kanagawa/summer-day/summer-night). Added a palette-resolved `border`
+  field (`{active, inactive}`) to the theme schema (`theme.nix`), consumed
+  solid in `hyprland.nix`, and declared it in every preset so a switch
+  always replaces it. All six identity themes now match legacy exactly.
 - **Waybar shows non-existent workspaces:** in summer-night/summer-day the
   bar renders every workspace icon up-front via `persistent-workspaces` /
   `all-outputs` in `themes/summer-{day,night}/waybar.jsonc`. Restore the