CL-6493: register the semantic color tokens

[TheGreatAxios]

Summary

apps/web imports react-ui's prebuilt styles.css for reset/theme/base but never react-ui's theme.css, so --success / --destructive (and --ok / --warn) exist only as plain :root custom properties inherited from that prebuilt sheet — never registered under Tailwind's @theme in apps/web's own build. Tailwind has no theme color to generate bg-success / bg-destructive utilities from, so data-[state=connected]:bg-success in packages/plugins-ui/src/installed-strip.tsx compiled to nothing and the plugin directory's connected-state dot was invisible.

• Added @import "@corbits/react-ui/theme.css"; to apps/web/src/tailwind.css, right after @import "tailwindcss"; — this is react-ui's own README-documented pairing for a consumer that runs its own Tailwind v4 build, so it registers --color-success/--color-destructive/etc. as real theme colors without duplicating preflight.
• Added @source "../../../packages/context-menu/src"; — that package is live-wired into the app's right-click menu (text-destructive, data-[highlighted]:bg-destructive/10) but was never scanned; it has no styles.css of its own so CL-6490's guard heuristic (which only checks imported stylesheets) doesn't catch it.
• Fixed the sibling data-[state=needs_attention]:bg-destructive on the same dot: Tailwind v4 converts an unescaped underscore in an arbitrary value to a space, so the generated selector matched [data-state="needs attention"] and never matched the real needs_attention DOM attribute. Escaped to needs\_attention.
• Fixed six call sites using text-danger-foreground (agent-skills-picker.tsx x2, agent-detail-page.tsx x3, agents-page.tsx x1) — danger was never a registered token anywhere (react-ui ships success/destructive/ok/warn, not danger), so this text has never rendered as destructive-colored. Replaced with text-destructive, matching the identical working pattern used elsewhere.

Before / after evidence (built apps/web CSS)

Before:

$ grep -oE '\.bg-success\{[^}]*\}' dist/assets/*.css
(no output)
$ grep -o '\[data-state=connected\][^{]*{[^}]*}' dist/assets/*.css
(no output)

After:

$ grep -oE '\.bg-success\{[^}]*\}' dist/assets/*.css
.bg-success{background-color:var(--success)}
$ grep -o 'data-\\\[state\\=connected\\\]\\:bg-success\[data-state=connected\][^}]*}' dist/assets/*.css
data-\[state\=connected\]\:bg-success[data-state=connected]{background-color:var(--success)}

Also confirmed post-fix: needs_attention variant now matches [data-state=needs_attention] (literal underscore), context-menu's text-destructive/data-[highlighted]:bg-destructive/10 now compile, and all text-danger-foreground references are gone from the codebase.

Cousins sweep

Grepped product code for every (bg|text|border|ring|...)-{success,destructive,ok,warn,warning,danger,error,info} utility. Found and fixed the four classes above. This was one repeated stray token (danger) plus two other silent-failure instances of already-known bug classes (missing @source, unescaped underscore) rather than a new structural gap, so I did not extend scripts/checks/tailwind-source.ts — per CL-6493's own guidance, a stray token gets fixed directly rather than new tooling.

Test plan

• bun run build in apps/web succeeds before and after (both green)
• Grepped emitted CSS before/after for bg-success, the data-[state=connected]:bg-success variant, needs_attention, text-destructive, and text-danger-foreground — all confirmed
• bun run lint passes (0 errors, only pre-existing unrelated warnings)
• bun run check (full monorepo typecheck/lint/test) — running in CI; not held locally per timebox

DO NOT MERGE — reviewer should confirm CI is green before merging.

Fixes CL-6493