feat(rotatui): double-ruled gum UI, failure-resilient rituals, CI lint

[drawmeanelephant]

Summary

Follow-up to the Rotatui charm-stack work (#319). Fixes a latent bug where any failing ritual killed the whole TUI, unifies the visual language on a double-ruled border, and leans harder on the Gum feature set.

Bug fix — failed rituals aborted the TUI

rotatui.sh sets set -euo pipefail, but every spooky_spin/run_with_spin call site captured $? on the next line. Under set -e a non-zero return aborts before that line, so the ❌ RITUAL FAILED panel / log / pager never rendered and the process exited. It only ever looked fine because success paths never tripped it.

• Guard every capture site: spooky_spin ... || code=$?
• run_with_spin now stores status in RITUAL_STATUS and returns 0 (it already reports pass/fail)
• Wrap the menu dispatch in case ... esac || true so a stray failure returns to the menu

UI — consistent double-ruled framing

• New panel() / section_header() helpers; every panel, table, and header now shares one double-ruled border (no rounded borders remain)
• Main menu normalized to a consistent emoji gutter + fixed-width label column so descriptions line up (fixes the ⚙️ Initialize Env / 🏷️ Version Bump drift)

More Gum

• gum spin replaces the hand-rolled braille spinner; spinner varies per ritual, overridable with RK_SPINNER
• gum log for the Charm stack notice and inline diagnostics
• gum format --type markdown as the Tomb Peek fallback when glow is absent
• Tomb Peek style now matches the tomb's template: frontmatter (or default_template): light→light, pride/kawaii/flash/daisy→pink, spooky/necropolis/dark→dracula
• gum choose --no-limit for multi-target Book Binders
• gum filter --select-if-one --fuzzy for template selection
• themed confirm --affirmative/--negative labels throughout
• gum table --columns with a double border
• gum join --horizontal for two-up status cards, and gum format --type template for the colored freshness line
• Status script-health table is now interactive (gum table --return-column) and opens the selected script's doc page (or source) in gum pager
• add init and help rituals to the menu; Showcase derives its theme count

CI

• Add shellcheck rotatui.sh to the lint step (it wasn't covered before)

Validation

• bash -n rotatui.sh + shellcheck rotatui.sh clean (one targeted SC2016 disable for the intentional inner-bash expansion)
• bash rotkeeper.sh status
• bash rotkeeper.sh test — 3/3 layouts + contract/DIP/regression suites passed
• pty smoke runs: menu renders and exits cleanly; the System Status screen renders the joined cards + colored freshness line; gum table --return-column returns the selected script under a pty; a ritual runs through gum spin + panel + return to menu
• scripted check that all 21 menu options still match a dispatcher case pattern
• Verified all flags used are available in Gum 0.x; v2.0.0 has no CLI/UX changes

Notes

• Emoji cell width is terminal-dependent; if a specific glyph renders 1-cell the row can drift by one. Padding itself is now uniform.
• gum join is now used; no Gum subcommands remain unused.

[drawmeanelephant]

Added a follow-up commit (2159283) with the Gum wins: theme-matched peek, interactive script-health table → doc/source pager, gum join two-up status cards, gum format template freshness line, and per-ritual spinners. Lint + pty smoke re-run green.

[drawmeanelephant]

Added settle_terminal (commit 06949fb) to absorb the late Kitty-protocol reply that was leaking as ^[[?1u after gum spin (bubbletea #1627/#1749). It disables echo briefly post-spin and drains, then restores termios via a trap; no-op without a tty. Echo restoration verified under a pty.

[drawmeanelephant]

Reworked the leak mitigation (commit faf211d). The post-spin drain was too late — Bubble Tea v2 sends its capability probes before entering raw mode, so replies like ^[[?2026;2$y, ^[[?2027;4$y, ^[[?1u echo at spin startup (seen on both iTerm and Ghostty). Now echo is disabled before gum spin and held off through the spin and a short drain, then termios is restored via a trap. No tty → no-op. Verified: echo restored and the ritual→menu flow intact under a pty.