Add habit management to CLI and TUI - #231

Adds habit creation, editing, and deletion to the CLI and Calendar TUI so habits can be managed without returning to the web app. Existing complete/uncomplete behavior remains unchanged.

What changed

• Adds hey habit create, hey habit edit (update alias), and hey habit delete through the typed HEY SDK.
• Accepts weekday names or 0–6, validates HEY's supported icon/color values locally, and supports partial edits.
• Adds Calendar TUI forms for creating and editing habits, visible-habit selection, and confirmed deletion.
• Restricts TUI creation to the personal calendar and refreshes recordings after successful mutations.
• Preserves form and selection state after API failures so mutations can be retried.
• Updates command discovery, README/skill documentation, API coverage, and smoke coverage.

Scope

• TUI edit/delete applies to habits visible in the current calendar range because HEY does not expose a typed habit list/get API.
• Habit stop/resume and list/get are outside this card.
• No haystack or hey-sdk changes are required; hey-sdk v0.7.0 already provides the CRUD operations.

Validation

• GOWORK=off make test — passed
• GOWORK=off make lint — passed, 0 issues
• GOWORK=off make build — passed
• GOWORK=off make test-smoke — passed against app.hey.localhost:3003, including TestHabitCreateEditDelete
• Independent code review — no blocking or actionable findings

Delivery and risk

No migration, configuration, feature flag, or deploy ordering is required. Main review focus: Calendar TUI input/state routing and the shared icon/color/weekday validation.

Basecamp card: https://app.basecamp.com/2914079/buckets/48521764/card_tables/cards/10206892903

Summary by cubic

Add habit creation, editing, and deletion to the CLI and Calendar TUI so users can manage habits without the web app. Previously only completion/uncompletion was available; now full CRUD is supported, with TUI creation limited to the personal calendar and deletion requiring confirmation bound to the selected habit.

• CLI: adds hey habit create, hey habit edit (update alias), and hey habit delete; accepts weekday names or 0–6, validates icon/color locally (flag help lists accepted values), supports stdin for names, sends partial edits, and returns JSON summaries.
• Calendar TUI: adds create/edit forms (Tab/Shift+Tab to move, Enter advances, Ctrl+S to save); press a to create on the personal calendar, select visible habits with [/], edit with e, and delete with x twice. Delete confirmation is tied to the selected habit and resets on other keys, selection change, or recordings reload. After mutations, recordings refresh and notices show results; on API failure, forms keep values, selection stays put, and account switching is blocked only while saving/deleting.
• Models now include icon, color, and days; calls use Habits().Create/Update/Delete from hey-sdk.

Scope

• Manage actions target habits visible in the current calendar range; stop/resume and list/get remain out of scope.
• No migration, configuration, feature flags, or deploy ordering. Review focus: Calendar TUI input/state routing, deletion confirmation binding, mutation flow, and locking during saves.

^{Written for commit 709a396. Summary will update on new commits.}