Guides: graph analytics (views and algo.*) and time series, in SQL and openCypher - #389

Closes #388.

Two engine areas that the bindings reach only through queries (DSL-first, docs/api-access-methods.md) now have guides, each example a db.query/db.command call checked by a test that sends the exact statement printed in the page.

• docs/guide/graph-analytics.md: algo.* procedures without a view (PageRank with options, WCC and SCC, BFS, Dijkstra, degree and triangle count, Louvain, betweenness), Graph Analytical Views (CREATE, update modes, state polling, ALTER/REBUILD/DROP, IF NOT EXISTS), what a view serves and its caveats.
• docs/guide/timeseries.md: CREATE TIMESERIES TYPE with shards, retention, compaction interval and a downsampling policy, three insert forms, the async append_samples path and COMPACT, ts.timeBucket (with a time zone), ts.first/last/delta/rate/percentile/movingAvg, to_arrow, continuous aggregates.
• What the pages do not claim, because it was not verified: that a view serves a given count (the plan is the same with and without one), that retention and downsampling remove or roll up old samples (only the stored policy is checked), CCH shortest paths, and several ts.* functions beyond their syntax.
• mkdocs.yml nav, a pointer from graphs.md, rows in bindings/python/AGENTS.md, java-api-coverage.md and testing.md.
• Tests: test_guide_graph_analytics.py (13) and test_guide_timeseries.py (14); no skips.

Checked locally against the 26.10.2 engine: the 27 new tests, test_docs_examples.py and test_check_test_skips.py, bandit (low/low), pre-commit, the strict docs build.

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