Say how to install ccl_chromium_reader instead of failing with a traceback

[dchaudhari7177]

Refs #331 — option 3 only, and deliberately not a close.

The issue lists three options in preference order. 1 (ask CCL to publish to PyPI) and 2 (vendor it) are calls for the project to make, and neither is mine to decide. 3 is the "minimum hardening regardless of the choice", and it is worth having whichever way the other two go.

Before

  File "…/hindsight.py", line 22, in <module>
    from pyhindsight.analysis import AnalysisSession
  File "…/pyhindsight/analysis.py", line 18, in <module>
    from pyhindsight.browsers.chrome import Chrome
  File "…/pyhindsight/browsers/chrome.py", line 18, in <module>
    import ccl_chromium_reader
ImportError: No module named 'ccl_chromium_reader'

After

Hindsight needs ccl_chromium_reader, which is not on PyPI and so cannot be
installed automatically. Install it with:

    pip install git+https://github.com/cclgroupltd/ccl_chromium_reader.git

Without it, cache, IndexedDB, Session Storage and Local Storage cannot be
parsed. The frozen release binaries already bundle it; only pip installs need
this step.

[exited with code 1]

No traceback, exit 1.

How

chrome.py's import raises an ImportError carrying the command, and both entry points (hindsight.py, hindsight_gui.py) catch that one error and exit with the message alone. Any other ImportError is re-raised untouched, so a genuinely broken install still shows its own traceback rather than being mislabelled as a missing ccl.

The message says the release binaries already bundle it, because otherwise the natural next question is "then why does the exe work?".

Verified

Reproducing the pip-install-without-ccl shape on a machine that has ccl, via a sys.meta_path finder that makes the module unimportable, then importing each entry point:

	before	after
import hindsight	6-frame traceback ending in ImportError	the message above, exit 1
import hindsight_gui	same	same
with ccl present	imports fine	imports fine, main callable

pytest: 248 passed, 2 skipped, 80 subtests passed — unchanged.

What this does not do

Left open on purpose, and why the issue should stay open:

• The dependency is still undeclared, so pip install pyhindsight still needs a second command. That is options 1 and 2.
• ccl's 43 bare print() calls are still worked around by the stdout guard rather than fixed, and ccl_chromium_sessionstorage's None logger is still monkeypatched at runtime. Both need the control that only vendoring or an upstream change gives.

Happy to do the vendoring in a follow-up if that is the direction you want — including the sync script in the manner of regen-protos.sh — but that wants your decision first, not a PR that assumes it.