Normalize user-visible logging across initrd scripts and documentation so output
levels are applied consistently.

- Align STATUS/STATUS_OK usage for action start and success
- Reserve NOTE for user guidance requiring attention
- Keep WARN/ERROR messaging actionable and consistent
- Update doc/logging.md to match runtime behavior

Signed-off-by: Thierry Laurion <insurgo@riseup.net>

Relative to origin/master (c2fb345):
- Introduces wait_for_usb_security_dongle_vid() with visible countdown.
- Adds user-cancel path during wait (keyboard/serial).

Current state:
- Wait exits early once a known VID appears.
- Wait times out after 15 seconds to avoid indefinite boot stall.
- Branding fallback path remains unchanged.

Signed-off-by: Thierry Laurion <insurgo@riseup.net>

Relative to origin/master (c2fb345):
- Aligns pause_recovery() with hardened recovery checks.
- Drains serial input queue before launching recovery shell.

Current state:
- Buffered serial bytes are no longer interpreted as shell commands.
- PCR extension/auth path is preserved before shell handoff.

Signed-off-by: Thierry Laurion <insurgo@riseup.net>

Relative to origin/master (c2fb345):
- Replaces asymmetric script handling with PID-tracked respawn loop.
- Tracks process ids per console path and restarts only when dead.

Current state:
- Main and auxiliary consoles respawn predictably without tight loops.
- Existing cttyhack/agetty split is preserved.

Signed-off-by: Thierry Laurion <insurgo@riseup.net>

Relative to origin/master (c2fb345):
- Reintroduces DEBUG lines for critical startup branching decisions.
- Covers TPM/USB gating, recovery paths, and boot flow selection.

Current state:
- Early-boot decision points are observable in debug logs.
- Runtime behavior is unchanged; this is diagnostics-only.

Signed-off-by: Thierry Laurion <insurgo@riseup.net>

Relative to origin/master (c2fb345):
- GIT_BRANCH-derived token used in artifact names is sanitized.
- Slashes/whitespace in branch names no longer create invalid output paths.

Current state:
- Artifact basenames remain traceable to branch context.
- Build copy/install steps no longer fail on branch names like feature/foo.

Signed-off-by: Thierry Laurion <insurgo@riseup.net>

Correct DUK documentation from "128 characters" to "128 bytes" in runtime status/error messages and security/TPM docs. Add explicit notation of the brute-force space (2^1024) to clarify entropy magnitude.

The DUK is 128 bytes from /dev/urandom (1024 bits of entropy). Brute-force time grows exponentially with entropy: a 128-byte random secret has 2^1024 possible values, requiring an attacker to try about 2^1023 guesses on average.

Using the formula time ≈ 2^(H-1)/R (where H is entropy in bits, R is guesses/second):
- At 10^12 guesses/second, expected time is ~2^1023/10^12 seconds
- This is unimaginably longer than the age of the universe (~4×10^17 seconds)
- Every bit of entropy doubles the search space, making exponential growth the key property

For practical comparison: 80 Diceware words provide ~1032 bits of entropy, roughly comparable to 128 random bytes. Every attack rate is dominated by the exponential requirement.

Important caveat: this protection applies only to offline brute-force against a correctly stored secret. Online rate limits or poor storage would override these estimates.

Signed-off-by: Thierry Laurion <insurgo@riseup.net>