[FEATURE] Economy profile: one preset that makes restraint the default

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet — searches for economy/budget/cost-conscious mode presets returned no matching open request.
• [x] This is a single feature request (not multiple features)

Problem Statement

Cost-control tools exist (model tiers, effort settings, /fast, caching), but the default direction of the product is "do more": deeper research, more subagents, longer answers arrive out of the box, while restraint is opt-in and must be hand-written by the user. In practice our project's CLAUDE.md is roughly half brake-rules ("default to light research", "short answers", "read only the relevant line ranges", "don't spawn agents for single-file edits"). The party paying the bill is also the party who has to author the brakes — that asymmetry is the problem, not the absence of individual tools.

Proposed Solution

An economy profile — a single opt-in preset (e.g. claude --profile economy or a settings key) that flips the defaults: light research unless explicitly asked to go deep, conservative subagent spawning, targeted reads over full-file reads, concise responses. One switch instead of a page of hand-written brake rules; individual settings remain overridable.

Alternative Solutions

• Hand-authored CLAUDE.md brake rules — our current approach; works, but every team rediscovers and re-writes the same rules, and instruction-layer rules are the weakest enforcement point.
• Per-feature toggles (effort, model choice) — address magnitude, not the default direction.

Priority

Medium - Would be very helpful