🧹 Extract huge Inno Setup strings into template files

[Tcode-Motion]

🎯 What: Extracted the massive string literals defining Inno Setup scripts inside tools/packager/src/main.rs into separate .iss.template files (offline_installer.iss.template and online_installer.iss.template), and updated the code to use include_str! and str::replace().
💡 Why: Drastically improves maintainability and readability by separating the installer script data from the Rust packaging logic. It eliminates the need to escape curly braces ({{ and }}) that was previously required when using the format! macro, making the templates much easier to read and edit.
✅ Verification: Verified by compiling the packager (cargo check -p techscript_packager), running the linter (cargo clippy -p techscript_packager -- -D warnings), and running the full workspace test suite (cargo test --workspace) to ensure no regressions were introduced.
✨ Result: A cleaner, much smaller main.rs in the packager tool, and proper distinct files for maintaining setup templates.

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PR created automatically by Jules for task 11258952867716041347 started by @Tcode-Motion

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