Fix Backtest correctness issues and build guided documentation

[stefan-jansen]

Scope

Resolve milestone 6 correctness defects and provide an executable, example-led Backtest guide. The milestone plan remains in the private development sidecar; this PR contains the public implementation and validation artifacts.

Progress

• MaxDrawdownLimit(action="reduce") is reported as breached but nothing happens #103 Apply configured drawdown reductions through broker orders.
• to_fills_dataframe() drops the feed timezone, so fills cannot be joined back to the feed #104 Preserve feed timezone in fill exports.
• A long-to-short flip is charged as two orders, so a per-order commission applies twice #105 Charge a long-to-short flip as one commission-bearing order.
• Funding payments for perpetual futures #106 Apply perpetual futures funding payments.
• Daily bars from instruments with different session closes arrive as separate events #107 Support one decision across different daily close times.
• Establish reproducible tutorial data and example checks #108 Establish reproducible tutorial data and example checks.
• Replace the quickstart with a first completed backtest #109 Replace quickstart with a completed backtest.
• Teach order types and execution timing with one controlled strategy #110 Teach order types and execution timing.
• Teach multi-asset signals, rebalancing, and session choices #111 Teach multi-asset signals, rebalancing, and sessions.
• Teach commission, slippage, impact, and funding with gross-to-net results #112 Teach costs and funding with gross-to-net results.
• Teach accounts, sizing, and constraints across asset settings #113 Teach accounts, sizing, and constraints.
• Teach risk rules and stateful strategy behavior #114 Teach risk rules and stateful strategies.
• Teach profiles and bounded framework comparisons #115 Teach profiles and bounded framework comparisons.
• Teach result exports and downstream analysis #116 Teach result exports and downstream analysis.
• Repair the Book Guide and connect every guide page to verified sources #117 Repair the Book Guide and link guide pages to verified sources.
• Qualify and publish the integrated Backtest release and documentation #118 Qualify and publish the integrated release and documentation.

Verification

• Local test suite: 2,209 passed, 13 skipped. Coverage suite after the funding artifact recovery test: 2,208 passed, 9 skipped, 5 deselected; global coverage 87.25%, result.py branch coverage 89.08%; the critical-module gate passes.
• Synthetic correctness: 66 pass, 2 unsupported. Real-strategy parity: 17 of 17 required framework pairs pass. Large-scale evidence and generated parity claims validate.
• Ruff, ty, strict MkDocs build, 22 pinned book paths, all installed-wheel core examples, and the optional diagnostic example pass.
• Two builds of wheel 0.1.9.dev25+g8343029f6 and its source distribution have identical hashes and pass the artifact content check. Rendered docs identify commit 8343029. All 43 remote PR checks have completed successfully or with their documented skip on this commit, including package build, coverage, compatibility, qualification, and public parity.

Issue closure on merge

Closes #103
Closes #104
Closes #105
Closes #106
Closes #107
Closes #108
Closes #109
Closes #110
Closes #111
Closes #112
Closes #113
Closes #114
Closes #115
Closes #116
Closes #117

Issue #118 remains open until the release artifact and deployed documentation are verified under the separate publication approvals.

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