fix: reset filled-order limits on the broker session day - #213

A filled-order limit could remain latched past the symbol's session reset, rejecting valid evening orders even when the correct exchange timezone and session were supplied.

Use one broker-day key across order placement, filled orders, and direct market closes. The key follows the unmerged symbol session clock, so a futures holiday daily bar can stay combined while the broker renews its order budget. Continuous-session fallback, other risk-day rules, and the indicator/security calendar remain unchanged. The shared helper is internal C++; the C ABI is unchanged. Update the README with the measured round 29 scoreboard.

Validation on final a752fef5b529ce3ff942717e8c6cda322fd9ccba:

• Cloud Run measures all 4,190 probes: 4,172 excellent / 18 strong / zero moderate. EURUSD JOAT improves to 100% matching and zero count gap; the other 4,189 canonical results are unchanged.
• Final and preceding corrected full sweeps have identical trade CSVs, grades, input hashes, and lane settings for all 4,190 probes. README totals: 2,817,239 matched / 2,819,967 TradingView trades; EURUSD 15m: 367 excellent / 6 strong.
• Covered TradingView controls verify summer/winter session boundaries, continuous sessions, equities, and the futures holiday reset while time("D") stays unchanged. 222/222 tests pass, including 253 focused assertions; C ABI and build freshness pass.
• Exact-final Grok 4.6 high review: P0/P1/P2 = 0. Formal gate pineforge-pr-gate-jqrjn: PASS, target score +1, all 704 hard probes unchanged, zero tolerated exceptions. Snapshot: a75857788f0ed079e946893e5882fde4fe9dd58346a04ffd08562a0c5a4958ed.

Codegen remains 3fd97fe28abd7b191cb376d9f5db4e056fcfae4b. Grading metrics, verifier, harness, population, tapes, symbol inputs, and FX policy are unchanged. Runtime eligibility has no strategy, symbol, date, or benchmark-ID conditions.