feat(terminal): first-class Ghostty + Termux support; adopt upstream AAA palette

[Rynaro]

Summary

Makes terminal emulators first-class in Potions — Ghostty (Linux/macOS) and Termux (Android) — with live theme rotation and quality-of-life wiring, and adopts the upstream alchemists-orchid.ghostty palette as the canonical theme.

Built on three product decisions:

1. Adopt the upstream palette as canonical (Nord-based, WCAG-AAA, astigmatism-friendly) across every surface.
2. Manage Ghostty's config via a backup + config-file include.
3. Configure-only — Potions never installs an emulator, only themes one that is present.

Palette — single source of truth

The upstream palette becomes the SoT for shell / NeoVim / Zellij / terminals. The theme system's design made this clean: the resolver whitelist already accepts any COLOR_* token and the compiler auto-emits every .color entry, so adding an explicit ANSI-16 + cursor/selection layer to the .tokens.json sources is pure data — no parser/compiler logic change. All three variants (dark #2e3440, white = upstream light #fafbfc, sepia #f5f0e6) are now byte-faithful to the upstream theme. Semantic tokens + nvim component shades retuned to the same hue family.

Adapters

• shell / Zellij / terminal adapters read the explicit COLOR_ANSI_* tokens (byte-faithful per variant) + cursor/selection; shell adds OSC 12 (cursor).
• Ghostty output split: ghostty-colors (palette + cursor/selection, per theme) and a managed ghostty.conf (config-file include + QoL: cursor-style, unfocused-split-opacity, shell-integration, macos-option-as-alt, Zellij tab keybinds).
• New theme_gen_adapter_termux writes ~/.termux/colors.properties and applies it live via termux-reload-settings; self-gates to a no-op off-Termux. Added to the generator targets.

potions terminal command

New .potions/lib/terminal/manager.sh (mirrors theme/manager.sh): configure-only, idempotent, backup-first wiring.

• terminal setup [ghostty|termux|all|--auto] — wires the Ghostty include and the Termux extra-keys row.
• terminal status — reports detection + wiring.
• install.sh / upgrade.sh run terminal setup --auto after theme regen; bin/potions routes terminal; both help paths list theme + terminal.

Docs

• TERMINAL_SETUP.md gains first-class Ghostty + Termux sections; README note.
• docs/color-palette.md regenerated.

Test plan

• ./test.sh — 249/249 pass (new: ANSI-16 faithfulness, Ghostty cursor/selection + managed config, Termux colors.properties on/off gate, terminal-setup idempotency + backup).
• scripts/compile-themes.sh --check clean; --docs in sync.
• End-to-end smoke through bin/potions: theme cycle repaints all surfaces; terminal setup ghostty backs up + wires once (idempotent); all three variants byte-faithful.
• .version 2.13.1 → 2.14.0; .checksums regenerated, sorted, no drift (install.sh, upgrade.sh, bin/potions changed).
• .gitignore allowlists .potions/lib/terminal/ (default-deny tree — would not ship otherwise).

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