One forge: the mode switch leaves; old ?mode= addresses redirect; the depth row gains Runs and Terminal #906

Closes #603

One forge: no studio/dev mode. An app speaks studio words, a plain repository speaks git words, and every depth is a link away on the same page.

Removed

• src/web/mode.ts, the forge_mode cookie, ctx.mode, the header mode toggle and its CSS
• POST /mode (modeSubmit, backTo) — now 404
• the dev-only palette list (one palette: the union, incl. New repository, New organization, Front page, Asks you)

Old URLs keep working: any GET with ?mode= answers 303 to the same address without it and clears a leftover forge_mode cookie. API paths untouched.

Depth row (repo tab strip, every repo): Files, Changes, Runs, and Terminal (/settings/keys#terminal, shown when signed in and this forge has an SSH listener). Agents reach the same depths through existing MCP tools (here, tell, asks, feed, map, now) and git over HTTPS.

Tests: new there is one forge (#603) (redirect, cookie cleared, POST /mode 404, depth-row hrefs) and an old ?mode=dev address is the same page without it (#603); studio, studio-words, web-origins updated, not deleted.

Looks at 390 and 1280: /alice/notes?mode=dev lands on /alice/notes, no toggle, Files/Changes/Runs links present; /alice/lib (no app) shows git words and Run as an app.

Hot file: src/http/server.ts.

🤖 Generated with Claude Code