feat(experiments): add read commands and development API routes

[joshdholtz]

Why

Expose the existing development v2 experiment reads to humans and agents. The endpoints stay in the development OpenAPI overlay.

First PR in the stack: #179 → #180 → #181.

Changes

• Add typed list, show, and results API reads and rc experiments list|show|results.
• Render variants, audience, placements, and a chronological timeline in show.
• Render total-segment metrics plus Chance to Win and 95% lift intervals in human results; preserve the full response in --json.
• Normalize documented platform aliases, warn on unknown platforms, and document exposure-status values.
• Add output snapshots and API/CLI coverage.

Review note

The shared table-width fix measures visible Unicode width. It also changes spacing in existing app-list snapshots and previews; those files are included so the output stays aligned.

Verification

go test ./..., go vet ./..., make gen, and make preview passed locally after rebasing onto current main.

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Note

Medium Risk
Read-only API surface, but touches shared CLI output formatting and permission-sensitive show fallback; development-gated endpoints may differ from production behavior.

Overview
Adds read-only rc experiments list|show|results against development v2 experiment endpoints, wired through a new ExperimentsService and registered on the normal CLI surface (with overlay/coverage docs updated).

show renders variants (up to four offerings), audience/targeting, placements, setup, and a chronological timeline; it prefers expand=offering.paywall and falls back to a plain GET with a warning when offerings read is forbidden. results prints total-segment metric tables, chance-to-win / lift intervals, and predicted LTV in human mode, with full sections/segments in --json; filters normalize platform aliases and country/currency casing, validate exposure-status, and warn on unknown platforms.

Also fixes table/card padding to use Unicode display width (lipgloss.Width), which updates a few existing app-list snapshots; snapshot harness now runs root with a shared stdout/stderr writer for stable ordering.

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