Correct the coverage gates the guide advertises

The documented gates had drifted well below the real ones: the backend gate
reads 80 in the workflow, not 50, and the frontend thresholds are 96 lines
and statements, 91 functions, 92 branches, not the 80/85 pair recorded here.
Anyone trusting the old numbers would think they had headroom that CI does
not grant. The frontend type-check command is also named correctly now, since
invoking tsc through npx picks up a newer compiler and fails spuriously.

CLAUDE.md

@@ -125,19 +125,19 @@ uv run ruff format --check .     # format check
 uv run pytest                    # tests with coverage (config in pyproject.toml)
 ```
 
-CI gate: `--cov-fail-under=50` today (current total ~52%), climbing toward **90** as tests land. Don't lower it — only raise when coverage grows.
+CI gate: `--cov-fail-under=80` today (current total ~84%), climbing toward **90** as tests land. Don't lower it — only raise when coverage grows.
 
 **Frontend** (from `frontend/`):
 
 ```bash
-npx tsc --noEmit                 # type check
+npm run typecheck                # type check (never npx tsc: it resolves a newer TS and emits a bogus TS5101)
 npm run lint                     # ESLint, zero warnings
 npm run coverage                 # Vitest with coverage
 ```
 
 CI gates (measured baseline after `src/pages/**` inclusion):
-- lines: **80%** | functions: **85%** | branches: **85%** | statements: **80%**
-- These act as a regression ratchet, not a target. Current state (82.36% lines, 88.5% functions) shows pages are now visible and poorly covered (Auth, Tips, DevFetch at 0%); the intent is to raise thresholds over time, not to churn tests today.
+- lines: 96 | functions: 91 | branches: 92 | statements: 96
+- These act as a regression ratchet, not a target. Current coverage (97.26% lines/statements, 93.05% functions, 93.51% branches) exceeds thresholds; gates must never be lowered to pass.
 
 ### WHO RUNS THE VERIFICATION COMMANDS (cost rule)
 
@@ -156,7 +156,7 @@ needed is reading pass/fail and the failure output. Paying a large model to sit
   than burning a large model on them.
 
 This applies to the full-suite verification runs: `uv run pytest`, `uv run ruff check .`,
-`uv run ruff format --check .`, `npx tsc --noEmit`, `npm run lint`, `npm run coverage`,
+`uv run ruff format --check .`, `npm run typecheck`, `npm run lint`, `npm run coverage`,
 `npx vitest run`, and `uv run alembic upgrade head`.
 
 It does **not** apply to quick diagnostics while you are mid-task — reading a single file, a