actibase (development version)

New acti_standardize_epoch() (and acti_standardise_epoch()) converts an epoch given as a number, a string ("1 min", "30s", "1 hr"), a Duration/Period, or a difftime into a number of seconds/minutes/ hours/days or a floor_date()/seq()-ready string.
actibase now requires lubridate (>= 1.9.0), the first version whose floor_date() supports the absolute units ("90 aseconds") that acti_standardize_epoch() can return.
The internal tzoffset_to_tz() now uses the correct inverted Etc/GMT sign convention ("-05:00" is "Etc/GMT+5"), matching actiread.
acti_flag_interval_jump() now defaults to verbose = TRUE.

actibase 0.8.0

flag_qc_all() is kept as an alias of acti_flag_qc_all() so that packages using the old name keep working; it will be deprecated later.
acti_fill_zeros() gains method = "actilife", which fills only all-zero runs at least one second (sample_rate rows) long, as in idle sleep, and keeps shorter runs (e.g. a single recorded (0, 0, 0) sample) as ActiLife does. The default method = "all" is unchanged.
get_sample_rate() now uses a message, not a warning, when it guesses the sample rate from the timestamps.

Add acti_flag_cdc_labels() to map existing logical QC columns to CDC-style NHANES PAM letter codes.
Document the CDC NHANES PAM flag mapping in the README and a package vignette, including known differences from CDC output.
Standardize accelerometer axis columns named X/Y/Z, x/y/z, acc_X/acc_x variants, or acceleration_X/acceleration_x variants.
Fail when upper- and lowercase versions of the same axis are both present. Warn once and prefer X/Y/Z when a complete canonical triplet and a complete acc_* or acceleration_* triplet are present.
Add clearer names for adjacent device-limit sample flags and axis-specific contiguous device-limit runs; retain the former names as compatibility wrappers.

Preserve missing values while applying minimum run lengths to logical QC flags.
Return an empty data frame when all rows are removed by leading-zero trimming.
Reject HMS times outside a single day instead of wrapping them to another minute.
Return a typed empty data frame when splitting an empty set of intervals.
Make the flag helpers configurable for different devices and sample rates. Sample rate defaults to NULL and is resolved through get_sample_rate() when continuity checks need it.
Add general helpers for device-limit counts in caller-defined windows, contiguous device-limit runs, adjacent invalid periods, and repeated samples. CDC threshold values are used only in regression tests.
Respect the minimum run length when an entire logical vector is TRUE.
Break contiguous sample runs at timestamp gaps using the resolved sample rate.
Add optional per-axis spike indicators and implement time-window spike counts using local extrema, a large-change threshold, and a caller-specified count.
Return axis-specific interval-jump indicators and process raw samples in bounded window chunks to limit temporary memory use.
Set the default minimum run for impossible-gravity flags to seven samples, use the device dynamic range to exclude clipped readings, and require the range from an argument or data metadata.
Prefix flagging functions with acti_ and standardize their input argument to data; use min_count and window_seconds for window-count and duration arguments.

Fix for create_day_inclusion – number of observed minutes was wrong.
Added transformations for add_day_inclusion and min_required as attribute for create_day_inclusion.
Roxygen: list(markdown = TRUE) added to the DESCRIPTION.

New helpers for time: acti_day_index acti_day_start acti_split_intervals_at_midnight acti_repeat_time_of_day acti_time_of_day acti_minute_to_hms acti_hms_to_minute acti_time_to_minute.