chore(packages): remove 2 zero-consumer config packages

Item #21 in the pre-launch audit suggested merging the four
config-y packages (shared-config, shared-tsconfig, shared-vite-config,
shared-drizzle-config) into a single @mana/build-config with
conditional exports. The first reality-check of the item counted
package.json declarations and reported 5 total consumer relationships.
A second reality-check while implementing — grep over actual .ts /
.svelte / .json imports — showed two of the four packages are dead:

  - packages/shared-config/ (598 LOC, 4 TS files)
    Declared in apps/mana/apps/web/package.json but never imported
    anywhere. Stale dep from before the consolidation.

  - packages/shared-tsconfig/ (5 JSON tsconfig presets)
    Zero references anywhere. Not extended by any tsconfig.json,
    not declared in any package.json. Pure Pre-Consolidation
    leftover.

The remaining two packages were left intact:
  - shared-vite-config (3 real consumers in vite.config.ts files)
  - shared-drizzle-config (1 real consumer in mana-media)

They cover different toolchains (Vite SSR config vs drizzle-kit
generator config) — merging them into a single build-config would
be cosmetic, not a real reduction in complexity. Audit's "merge to
1" goal was based on the inflated consumer count and is no longer
worth doing.

Verification:
  - pnpm install completes cleanly
  - apps/api type-check still 0 errors
  - packages/shared-hono type-check still 0 errors

Net: 4 → 2 config packages, ~700 LOC dead code removed.

Also closes item #26 (non-root pnpm-lock.yaml status) — already
done in commit 034a07d16, doc was just out of date. Audit is now
29/29 items fully processed.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/mana/apps/web/package.json

@@ -55,7 +55,6 @@
 		"@mana/shared-auth": "workspace:*",
 		"@mana/shared-auth-ui": "workspace:*",
 		"@mana/shared-branding": "workspace:*",
-		"@mana/shared-config": "workspace:*",
 		"@mana/shared-error-tracking": "workspace:*",
 		"@mana/shared-i18n": "workspace:*",
 		"@mana/shared-icons": "workspace:*",