Add user manual Part 1; cross-reference the two tool guides

Part 1 covers the parts of the application that have been stable for months:
signing in and district scoping, the map screen, navigation, base maps, layers,
locations, measuring, an orientation to Analyse, exporting, working offline,
GPS, settings, and a troubleshooting table. Nine pages, built from the Analyse
tutorial so it matches the existing guides rather than looking like a new
document — same cover, header, footer, headings, call-outs and tables.

Held back deliberately: the drawing and digitising tools, which changed across
v15-v23 and want a settling period in the field, and anything depending on
server endpoints that are not deployed. Those are Parts 2 and 3. The manual is
stamped with the application version it describes (23), because an older
installation behaves differently around the toolbar.

Section 7.2 documents the Markers layer behaviour, including that switching it
off yourself will not stick, since that is the part most likely to look like
data loss.

On the two guides: I had said they were stale because they described the removed
Add Location button. That was wrong — neither mentions it, and I asserted it
without checking. What they did need was smaller. Both gain a Related documents
section so the three files read as a set, and the Analyse guide's manual-selection
instruction now says where the Select tool is, which it could not have when it
was written before the toolbar was banded into groups.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

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