Explain install_and_run Installation

install_and_run.md

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+#  PPTX Image Compressor – Installation Logic
+
+## 1. Intro – One Line Summary
+
+> The script selects the best available Python environment, falls back to a self-installed embedded runtime if necessary, ensures `pip`, installs `svg-polish` when possible, and runs the application with graceful degradation.
+
+## 2. Lightweight Overview
+
+```text
+START
+│
+├─► Find usable Python
+│     ├─ venv (active / local)
+│     ├─ system Python
+│     └─ fallback: download embedded Python
+│
+├─► Ensure pip works
+│     ├─ pip exists → OK
+│     ├─ ensurepip → try fix
+│     └─ get-pip.py → fallback fix
+│
+├─► Install dependency
+│     └─ svg-polish (optional but preferred)
+│
+├─► Run main script
+│
+└─► END
+```
+
+---
+
+## 3. Detailed Logic Tree
+
+```text
+START
+│
+├─► [A] Pre-check: caesiumclt
+│     ├─ found → continue
+│     └─ not found → EXIT
+│
+├─► [B] Python resolution (priority-based)
+│     │
+│     ├─ Active venv (VIRTUAL_ENV)?
+│     │     └─ use it ✅
+│     │
+│     ├─ Local ".venv"?
+│     │     └─ use it ✅
+│     │
+│     ├─ Local "venv"?
+│     │     └─ use it ✅
+│     │
+│     ├─ System Python (python.exe, excluding WindowsApps)?
+│     │     └─ use it ✅
+│     │
+│     ├─ Python launcher (py.exe)?
+│     │     └─ use py -3 ✅
+│     │
+│     ├─ Existing embedded Python?
+│     │     └─ use it ✅
+│     │
+│     └─ NONE FOUND →
+│           ├─ Download embeddable Python
+│           ├─ Extract to python-embed
+│           ├─ Fix isolation (enable "import site")
+│           └─ use it ✅
+│
+├─► [C] Validate main script exists
+│     ├─ missing → EXIT
+│     └─ exists → continue
+│
+├─► [D] Ensure pip availability
+│     │
+│     ├─ pip works?
+│     │     └─ YES → continue ✅
+│     │
+│     └─ NO →
+│          ├─ try: ensurepip
+│          │     ├─ success → ✅
+│          │     └─ fail →
+│          │
+│          └─ if embedded Python:
+│                ├─ download get-pip.py
+│                ├─ execute it
+│                ├─ remove file
+│                └─ re-check pip
+│
+│          ├─ still no pip →
+│          │     └─ WARN: disable SVG compression
+│          │
+│          └─ pip available →
+│                ✅ continue
+│
+├─► [E] Install dependency
+│     ├─ install svg-polish
+│     │     ├─ success → ✅ SVG enabled
+│     │     └─ fail → ⚠ SVG disabled
+│     │
+│     └─ optional debug: pip list
+│
+├─► [F] Run application
+│     ├─ execute Python script
+│     ├─ capture return code
+│     ├─ success → "Fertig"
+│     └─ error → report exit code
+│
+└─► END
+```