Unify installer colors with vim/shell palette and clean up output

- Replace BLUE/CYAN/CYAN_BOLD with TEAL/TEAL_BOLD (#2CB494) to match
  the primary accent used across vim, zsh prompt, tmux, and fzf
- Update BLUE (#0C48CC -> #4068D4) then merge into TEAL
- Update RED (#F40404 -> #F88C14) to match vim/shell error orange
- Rename GREEN to grey-blue (#7290B8) for [PASS] messages
- Format all raw echo output with log functions or log_quote
- Suppress sudo prompt when credentials are already cached
- Add missing log_pass to 22-zsh.sh and 23-stow.sh
- Convert raw 'already installed' echos to log_skip (7 scripts)
- Pipe SSH key and mise output through log_quote
- Suppress noisy bat cache and mise WARN output
- Match fastfetch colors to palette (teal logo, grey-blue keys)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

install.d/70-cca.sh

@@ -11,6 +11,6 @@
 if ! echo "$BREW_CASKS" | grep -q "^colour-contrast-analyser$"; then
     brew install --cask colour-contrast-analyser
 else
-    echo "Colour Contrast Analyser (CCA) is already installed."
+    log_skip "CCA already installed"
 fi
 log_pass "CCA installed"