refactor: reorganize keymaps into semantic namespaces

Restructure keybindings for improved discoverability and consistency
with WezTerm/XMonad configurations. Separate keymaps from plugin
configurations following single responsibility principle.

Changes:
- Create keymaps/ directory with semantic grouping:
  - general.nix: leader setup, page navigation
  - buffers.nix: buffer operations (bq, bQ, bl)
  - windows.nix: window operations (ws, wv, wq, wQ, wm)
  - find.nix: telescope find operations (ff, fg, fh, fc)
  - git.nix: unified git operations from gitsigns/fugitive/telescope

- Adopt consistent q/Q pattern across containers:
  - bq/bQ for buffer quit (current/all others)
  - wq/wQ for window quit (current/all others)
  - Mirrors WezTerm's LEADER+p q / LEADER+t q pattern

- Extract keymaps from plugin files:
  - telescope.nix: config only, keymaps moved to find.nix
  - fugitive.nix: config only, keymaps moved to git.nix
  - gitsigns.nix: config only, keymaps moved to git.nix
  - snacks.nix: config only, keymaps moved to buffers.nix
  - maximize.nix: config only, keymap moved to windows.nix

- Remove smart-splits.nix (functionality replaced by native window ops)

- Maintain navigation on dedicated modifiers (Ctrl+arrows/PageUp/PageDown)
  for consistency with WezTerm (ALT) and XMonad (Super)

config/keymaps/buffers.nix

@@ -0,0 +1,70 @@
+{...}: {
+  keymaps = [
+    # Buffer namespace indicator for whichkey
+    {
+      mode = ["n"];
+      key = "<leader>b";
+      action = "<NOP>";
+      options = {
+        desc = "+buffer";
+      };
+    }
+
+    # Buffer deletion
+    {
+      mode = ["n"];
+      key = "<leader>bq";
+      action = {
+        __raw = "function() require('snacks').bufdelete() end";
+      };
+      options = {
+        desc = "Quit current buffer";
+        silent = true;
+      };
+    }
+
+    {
+      mode = ["n"];
+      key = "<leader>bQ";
+      action = {
+        __raw = "function() require('snacks').bufdelete.other() end";
+      };
+      options = {
+        desc = "Quit all other buffers";
+        silent = true;
+      };
+    }
+
+    # Buffer navigation (moved from keymaps.nix)
+    {
+      mode = ["n"];
+      key = "<C-Left>";
+      action = ":bprevious<CR>";
+      options = {
+        desc = "Previous buffer";
+        silent = true;
+      };
+    }
+
+    {
+      mode = ["n"];
+      key = "<C-Right>";
+      action = ":bnext<CR>";
+      options = {
+        desc = "Next buffer";
+        silent = true;
+      };
+    }
+
+    # Buffer listing
+    {
+      mode = ["n"];
+      key = "<leader>bl";
+      action = "<cmd>Telescope buffers<CR>";
+      options = {
+        desc = "List buffers";
+        silent = true;
+      };
+    }
+  ];
+}