fix(web): wire API reachability, lenient string search params, sidebar state, chart and cache memoization - #2445

🟢 Confidence 10/10 · safe to merge. Mechanical, well-tested changes: each new behavior has a test and the cache memoization is a pure function of the rows array.
_{no findings · tests covered · risk medium}

Wires the API reachability clock the HTTP client writes into the warehouse layer, makes string search params accept an unquoted number/boolean/null, reads the sidebar cookie at boot, and memoizes bar-chart rows and cache use times. Safe to merge.

• withRequestTimeout marks an origin reachable on any response, unreachable on transport failures
• StringParam accepts number, boolean and null and prints them back as text
• shell.flags reads sidebar_state so a collapsed sidebar stays collapsed
• rowsCache and collectUnused keep chart rows and prune cache use times

Before merge

• Manual · Check the collapsed sidebar and a hand-written ?userId=12345 link in the preview:web deploy; nothing was run in a browser

_{7f3f5b0 · Reply "won't fix" to dismiss a finding, or mention @maple-review-bot to ask about one.}